Group Title: effects of secondary sewage effluent on the water quality, nutrient cycles and mass balances, and accumulation of soil organic matter in cypress domes /
Title: The Effects of secondary sewage effluent on the water quality, nutrient cycles and mass balances, and accumulation of soil organic matter in cypress domes
CITATION PDF VIEWER THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00099514/00001
 Material Information
Title: The Effects of secondary sewage effluent on the water quality, nutrient cycles and mass balances, and accumulation of soil organic matter in cypress domes
Physical Description: xxii, 287 leaves : ill., maps ; 28 cm.
Language: English
Creator: Dierberg, Forrest Edward, 1944-
Publication Date: 1980
Copyright Date: 1980
 Subjects
Subject: Wetland ecology   ( lcsh )
Sewage disposal   ( lcsh )
Sewage -- Purification   ( lcsh )
Environmental Engineering Sciences thesis Ph. D
Dissertations, Academic -- Environmental Engineering Sciences -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis--University of Florida.
Bibliography: Bibliography: leaves 268-286.
General Note: Typescript.
General Note: Vita.
Statement of Responsibility: by Forrest Edward Dierberg.
 Record Information
Bibliographic ID: UF00099514
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000099141
oclc - 06936483
notis - AAL4591

Downloads

This item has the following downloads:

PDF ( 12 MBs ) ( PDF )


Full Text











THE EFFECTS OF SECONDARY SEWAGE EFFLUENT ON THE WATER QUALITY,
NUTRIENT CYCLES AND MASS BALANCES, AND ACCUMULATION OF SOIL
ORGANIC MATTER IN CYPRESS DOMES








BY

FORREST EDWARD DIERBERG


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL
OF THE UNIVERSITY OF FLORIDA IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY



UNIVERSITY OF FLORIDA

1980














ACKNOWLEDGMENTS

This investigation was funded by a grant through the Center for

Wetlands jointly sponsored by the RANN Division of the National

Science Foundation and the Rockefeller Foundation.

I am especially grateful to the chairman of my supervisory com-

mittee, Dr. P. L. Brezonik, for his constructive suggestions on the

experimental work and preparation of this manuscript.

I would also like to thank the other members of my committee for

their help, especially Dr. K. C. Ewel with respect to the decomposi-

tion model and Dr. Graetz for his interest and support on various

aspects of the nitrogen cycle.

I also want to express sincere appreciation to Dr. H. T. Odum

for his continuous financial commitment during the course of this

investigation.

It is impossible to acknowledge each individual who in some way

assisted in the development of a dissertation of this nature. This

especially applies to the untold scores of graduate students and tech-

nicians who performed nitrogen analyses on the AutoAnalyzer. How-

ever, some individuals deserve special recognition for their help.

Appreciation is extended to Neil Carriker, who initiated me into the

subtleties of sampling swamps, to Charles Fellows, for his many help-

ful suggestions and serving in the essential role of confidant, to

Chuck Hendry and Eric Edgerton, whose assistance helped make the rain-

fall/thrufall section of higher quality, and to Pete Straub, Steve








Weeks and Steve Hall, who assisted me in both field sampling and lab

analyses. Klaus Heimburg deserves special recognition for his

patience and helpfulness in unraveling some of the hydrologic per-

plexities. Others whose efforts helped make possible this disser-

tation include Joan Breeze for her expeditious typing of the rough

draft; Philip J. d'Almada and Dr. Ken Portier for their statistical

expertise; Dr. Walter Judd and Shirley Kooijman for their botanical

assistance; and Curt Pollman for his mercurial efforts in essential

liaison work.

Lastly, my wife and son deserve special recognition for their

sacrifices during the course of this research effort. I also wish to

thank my wife for the highly professional job in typing the final

manuscript. Special credit belongs to my mother, whose devotion to

her children during untoward times made it possible for me to achieve

this goal.

It is no understatement that without the zeal, wisdom and con-

stant support shown by the above-named colleagues, committee members,

and family, this investigation would not have been completed.
















TABLE OF CONTENTS


ACKNOWLEDGMENTS . . . . . .


. . . . . . . ii


LIST OF TABLES . . . . . . . . . . .


.viii


LIST OF FIGURES. .. . . . . . . . . . . xii


ABSTRACT . . . . . . . .


CHAPTER


ONE INTRODUCTION . . . . . . . . . . . .

TWO AREAS OF INVESTIGATION, SAMPLING PROCEDURES, AND
ANALYTICAL METHODS. . . . . . . . .. ..


Site Description . . . . . . .
Sampling Procedures . . . . . .
Standing Waters, Sewage, and Shallow
Groundwaters . . . . . .
Runoff . . . . . . . .
Bulk Precipitation and Throughfall . .
Plant Biomass. . . . . . . .
Peat . . . . . . . . . .
Methods . . . . . . . . . .
Water Quality Parameters . . . . .
Nitrogen and Phosphorus Removal Studies..
Soil-solution studies . . . . .


Laboratory leaching studies . .
Cypress Leaf Decomposition .. ...
Model of Organic Matter Accumulation
Swamp Floor . . . . . .
Sediments and Peat . . .....
Denitrification . . . . .
Nitrification . . . . .
Surface sediments. . . ...
Surface waters .. .....
Nitrogen fixation . . . .


on the


Leaf litter, peat, and standing water ....
Floating and submerged macrophytes .. ....
Rhizosphere-endorhizosphere of woody
vegetation . . . . ... . .


5
9
. . . 5
. . . 9

. . . 9
. . . 14
. . 14

. . 17
. . 17
. . 18
. . 18
. .. 19










THREE THE EFFECT OF SECONDARY SEWAGE EFFLUENT ON THE SURFACE
AND GROUNDWATER QUALITY OF CYPRESS DOMES. . . .. 43

Standing Water Quality. ............ . .... 43
Surface Water Quality Following the Cessation
of Sewage Pumping to Sewage Dome 1. . . .. 53
Removal of Major Pollutants . . . . . .... 56
Conventional Treatment Plant/Dome System . . .. .56
Total organic carbon and biochemical
oxygen demand (BOD). . . . . .... 64
Nitrogen. . . . ... . . . . .. 66
Phosphorus. . . . . . . . . . 71
Sodium and potassium. . . . .... ..... 77
Calcium and magnesium . . . .... . .. 77
Sulfate . . . . . . . . . . 78
Chloride. . . . . . . . . . ... 78
Fluoride . . . . . . . . .. 79
Hydrogen sulfide . . . . . . . .. 79
Soil-Solution Studies . . . .. .. . . . 80
Laboratory Leaching Studies. . . .... .. . .. 82
Nitrate-nitrite . . . ... . . . . 83
Ammonium. . . . . . . . . . 90
Phosphorus. . . . ... .. . . . . 98


FOUR CHEMICAL CHARACTERISTICS OF NATURAL WATER IN A
FLORIDA CYPRESS DOME. . . . . . .

General Chemical Composition . . . .


Conductivity and Disso
Hydrogen Ions . .
Major Cations .. ..
Major Anions .. ...
Dissolved Gases . .
Oxygen . . . .
Carbon Dioxide . .
Hydrogen Sulfide . .
Minor and Trace Inorganic
Fluoride . . .
Iron . . . . .
Dissolved Silica .
Aluminum . . .
Dissolved Carbon . .
Major Nutrients . . .
Phosphorus . . ..
Nitrogen .......
Nitrate + nitrite
Ammonium .. ..
Organic nitrogen.


lved Solids. .. ..

. . . . ,


Components .. .


. . . . ,


. . . 102

. . . 102
. . . 102
. . . 104
. . . 109
. . . 113
. . . 116
. . . 116
. . .. 119
. . . 119
. . . 120
. . . 120
. . . 121
. . . 123
. . . 125
. . . 126
. . . 133
. . . .133
. . . 136
. . . 137
. . . 137
. . .. 139








FIVE DECOMPOSITION AND ORGANIC MATTER ACCUMULATION ON THE
SWAMP FLOORS OF A NATURAL AND SEWAGE-RECEIVING
CYPRESS DOME. . . . . . . . . ... .. 142

Litter Decomposition. ........ . . .143
Goodness of Fit of Simple Exponential and
Nonlinear Two-Compartment Models. . . . ... 143
Two-Compartment Parameter Estimates. . . . ... 146
Cypress litter. . . . . . . . .. 146
Duckweed litter . . . . . . . . 146
Cypress Leaf Litter Decomposition. . . . ... 150
Standing Stock of Organic Matter on Swamp Floor . . 152
Simulation of Model. .... . . . . . .154

SIX THE EFFECT OF SECONDARY SEWAGE EFFLUENT ON THE
NITROGEN TRANSFORMATIONS IN NATURAL CYPRESS DOMES . 157

Models of the Nitrogen Cycle. . . . . . ... 157
Nitrogen Fixation . . . . . . . . ... 160
Effectiveness of Various Metabolic Poisons on
Azolla Caroliniana. .............. 165
Aquatic Macrophytes. ................ 170
Leaf Litter, Peat, and Standing Water. . . .. 173
Rhizosphere-endorhizosphere of woody vegetation. . 183
Ammonification. . . . . . . . . . 195
Denitrification . . . . . . . .... . 199
Nitrification . . . . . . . ... . 206
Surface Sediments. . . . . . . . ... 207
Surface Waters . . . . . . . . ... 210

SEVEN NITROGEN AND PHOSPHORUS MASS BALANCE MODELS IN A
NATURAL AND A SEWAGE LOADED CYPRESS DOME. . . .. 214

Methods and Data Sources. . . . . . . ... 214
Nutrient Inputs. . . . . . . . . ... 214
Treated sewage. . . . . . . . . 214
Surface runoff. . . . . . . . ... 214
Bulk precipitation. . . . . . . ... 216
Nutrient Sinks . . . . . . . ... 217
Infiltration. . . . . . . . . ... 217
Denitrification . . . . . . ... 218
Surface overflow. . . . . . . . ... 218
Storages . . . . . . . .... .. .. 219
Cypress tree biomass. . . . . . . ... 219
Sediment. .. . . . . . .. .220
Results and Discussion. . . . . . . . ... 220
Sources. . . . . . . . ... ..... 220
Treated sewage. . . . . . . . ... 223
Nitrogen fixation . . . . . . .... 226
Surface runoff. . . . . . . . ... 228
Bulk precipitation. . . . . . . ... 231









Sinks. . . . . . . . ..... .231
Infiltration. . . . . . . . 231
Denitrification . . . . . . .... 232
Surface overflow. . . . . . . . ... 238
Storages . . . . . . . . . . . 239
Cypress aboveground biomass . . . . .. 239
Sediments . . . . . . . . 240
Cypress Domes As Nutrient Traps . . . . . 244
Nitrogen and Phosphorus Removal Efficiencies
in Sewage Dome 2 . . . . . . . 244
Mechanisms Whereby Nitrogen and Phosphorus Losses
are Minimized in a Natural Dome . . . ... 245

EIGHT SUMMARY AND CONCLUSIONS. . . . . . . . ... 246

APPENDICES

1 SUPPLEMENTARY INFORMATION ON THE ORGANIC MATTER
ACCUMULATION SIMULATION MODEL . . . . . . 255

2 NITROGEN CONTENT AND DENSITY OF THE PEAT FROM
AUSTIN CARY, GROUNDWATER CONTROL, AND SEWAGE
DOMES . . . . . . . . .. .. . . 262

3 FORTRAN IV COMPUTER PROGRAM USED IN THE CALCULATION
OF THE NET GROWTH OF ABOVEGROUND CYPRESS BIOMASS
COMPONENTS . . . . . . . . . . 267

BIBLIOGRAPHY . . . . . . . .... ........ 268

BIOGRAPHICAL SKETCH. ... . . . . . . . . .. 287






















vii















LIST OF TABLES


Table Page

2-1 List of physical and chemical parameters for
which analyses were performed . . . . . . . 9

2-2 Schedule for routine sampling . . . . . .... 1D

2-3 Parameters influenced by organic color and the
blanking procedures used to compensate for the
interference. . . . . . . ... . . 21

2-4 Analysis of the precision and accuracy of the
micro-Kjeldahl method used in the determination of
total N in the peat and decomposing leaf litter .... .30

2-5 Analysis of the precision and accuracy of the Tracor
222 and Tracor 550 gas chromatographs used in the
measurement of N20 during acetylene blockage
experiments . . . . . . . 33

2-6 Initial conditions of the experimental and control
bottles for the nitrification experiment on the surface
water from Austin Cary natural dome. Each value is
the mean of duplicate bottles . . . . . .... 35

3-1 Summary of the mean concentrations and standard
deviations of selected chemical parameters for standing
waters from March 1974 to May 1979. All values as
mg/L unless otherwise noted . . . . . .... 44

3-2 Summary of the mean concentrations and standard
deviations for selected parameters of composite
shallow groundwaters from April 1974 to May 1979.
All values as mg/L unless otherwise noted . . ... 51

3-3 Changes in water quality at the center station of
sewage dome 1 after cessation of sewage loading on
September 16, 1977. All values as mg/L unless otherwise
noted . . . . . . . . .. . . . 54

3-4 Summary of the mean concentrations and standard
deviations of selected chemical parameters throughout
the treatment plant/oxidation pond treatment system. All
values as mg/L unless otherwise noted . . . ... 61


viii









Table Page

3-5 Mean levels for selected chemical parameters of the
interstitial water taken at three depths from soil
tubes surrounding the cypress domes at the Owens-
Illinois site in November, December, January, May, and
August (1976-77). . . . . . . . . . . 81

3-6 Concentrations (mg/L) of pertinent chemical constituents
in the groundwater, treated sewage, and treated sewage
plus nitrate- and phosphate-spiked eluants used in the
sediment leaching study . . . . . . . . 84

3-7 Average concentrations, maximum concentrations, and
percent removals of nitrate plus nitrite nitrogen in
the leachates from 17-cm free-draining columns of
groundwater control dome sediments over a 21-month
period. . . . . . . . . ... ...... 86

3-8 Average concentrations, maximum concentrations, and
percent removals of ammonium nitrogen in the leachates
from 17-cm free-draining columns of groundwater control
dome sediments over a 21-month period . . . ... 93

3-9 Changes in the amounts of ammonium and total nitrogen
associated with the sediments in the leaching columns
during the 21-month leaching period . . . . .. 94

3-10 Selected chemical and physical properties of the
sediments used in nutrient removal columns (after
Coultas and Calhoun 1975) . . . . . . .... 96

3-11 Ammonium and total nitrogen mass balances (mg) for
the sediment leaching columns . . . . . .. 97

3-12 Average concentrations, maximum concentrations, and
percent removals of total phosphorus in the leachates
from 17-cm free-draining columns of groundwater control
dome sediments over a 21-month period . . . ... 100

4-1 Major ionic composition of Austin Cary cypress dome
surface water during study period (January 1974 -
June 1979). . . . . . . . ... .... 107

4-2 Ratios of selected constituents to chloride (by weight)
in the waters of Austin Cary cypress dome and comparison
waters. . . . . . . . . ... ...... 112

4-3 Dissolved gases in the surface waters of Austin Cary
cypress dome over time period March 1976 to July 1979 116

4-4 Minor ionic composition of Austin Cary cypress dome sur-
face water over the period January 1974 to June 1979. .. 120








Table


4-5 Composition of organic matter in the surface
waters of Austin Cary cypress dome. . . . . ... 127

5-1 Accumulation of root-free organic matter on the
swamp floor of Austin Cary natural dome . . . ... 154

6-1 Ethylene production by Azolla caroliniana using
various metabolic poisons . . . . . . .... 166

6-2 Ethylene production associated with Azolla
caroliniana blooms in Austin Cary natural dome,
sewage dome 2, and groundwater control dome ...... 171

6-3 Ethylene production associated with Utricularia sp.
in Austin Cary natural dome and groundwater control
dome. . . . . . . . . ... ....... 172

6-4 Estimated N2 fixed (C2H2) by peat (g N/m2-yr) for the
Austin Cary natural dome, sewage dome 2, and other
ecosystems. ..... . . . . .... 184

6-5 Weight loss, carbon concentrations, nitrogen concen-
trations, and nitrogen content of decomposing leaf
litter of Taxodium distichum var. nutans in Austin Cary
natural dome and sewage dome 2 for 1978-79. Each
number represents a mean of five bags. The numbers
enclosed in parentheses represent 1 S.E. of the mean .196

6-6 Relative advantages and disadvantages for different
methods used to measure the denitrification process . 200

6-7 Denitrification results in four experimental treat-
ments of peat from Austin Cary natural dome ...... 205

6-8 Most Probable Number (MPNi) of autotrophic nitrifiers,
ammonium and nitrate and nitrite levels in the surface
sediments of sewage dome 1, sewage dome 2, groundwater
control dome, and Austin Cary natural dome. . . .. 208

7-1 Annual variations in the nitrate plus nitrite nitro-
gen and total nitrogen loadings from the sewage effluent
piped into sewage dome 2 (April 1974 to March 1977).
Nitrogen values are g N/m2. . . . . . . ... 223

7-2 Total nitrogen, total phosphorus, and nitrate plus
nitrite levels in the surface runoff entering sewage
dome 1 (S1 stations), sewage dome 2 (S2 stations), and
Austin Cary natural dome (AC stations). Number within
parenthesis denotes the number of individual samples
whose mean is reported . . . . . . .... 229









Table


Page


7-3 Average nitrate plus nitrite balances (g N/m2-yr) for
sewage dome 2 during a three-year period and the
natural dome at Austin Cary during a four to five-
year period . . . . . . . .... .... 237

7-4 Increments in the aboveground biomass of cypress over
a three-year period (1976079). Each number is the
mean of 100 trees for each cypress dome except Austin
Cary, where 200 trees were sampled. . . . . ... 239

8-1 Summary of the nitrogen transformations in natural
and sewage-enriched cypress domes . . . . .... 249

A-i Documentation of storage and flows used in the
organic matter accumulation model for natural and
sewage-enriched cypress domes (Figure 5-4) ...... 255














LIST OF FIGURES


Figure Page

2-1 Locations of the two major study sites in
Alachua County . . . . . . . . ... . 6

2-2 Site plan, groundwater monitoring wells, soil tube
locations, and runoff sampling stations at the
Owens-Illinois research site. . . . . . . . 7

2-3 Sampling equipment and technique for sampling the
shallow groundwaters. . . . . . . . . ... 13

2-4 Site plan, groundwater wells (numbered dots), intersti-
tial water sampling stations, and the locations of the
bulk precipitation collectors at the Austin Cary
natural dome research site. . . . . . . ... 15

2-5 Precipitation collector . . . . . . . . 16

2-6 Apparatus used in total acidity titrations. . . .. 20

2-7 Setup for nutrient removal (left) and acetylene
blockage (right) experiments. . . . . . . ... 23

3-1 Average concentrations ( 1 S.E.) of organic carbon
and biochemical oxygen demand found at various points
within the conventional treatment plant/dome system
and in natural waters representing control sites over
the entire study period (March 1974-May 1979) . . .. 57

3-2 Average concentrations ( 1 S.E.) of total nitrogen
and total phosphorus found at various points within the
conventional treatment plant/dome system and in natural
waters representing control sites over the entire study
period (March 1974-May 1979). . . . . . . . 58

3-3 Average concentrations ( 1 S.E.) of calcium, magnesium,
sodium, and potassium found at various points within the
conventional treatment plant/dome system and in natural
waters representing control sites over the entire study
period (March 1974-May 1979). . . . . . . ... 59









Figure Page

3-4 Average concentrations ( 1 S.E.) of chloride,
sulfate, and fluoride found at various points within
the conventional treatment plant/dome system and in
natural waters representing control sites over the
entire study period (March 1974-May 1979) . . ... 60

3-5 Mean BOD5 levels in the surface waters of control
and experimental domes. Each point is the mean of
one or two edge stations for each dome, except Austin
Cary where only the center station is plotted. (G-1
is the groundwater control dome, S-1 is sewage dome 1,
and S-2 is sewage dome 2.). ........... ... . 65

3-6 Mean total nitrogen levels in the surface waters of
control and experimental domes. Each point is the mean
of one center and one or two edge stations for each dome,
except Austin Cary where only the center station is
plotted. (G-1 is the groundwater control dome, S-1 is
sewage dome 1, and S-2 is sewage dome 2.) . . . .. 67

3-7 Total nitrogen in the centers of sewage dome 1 (S-1C)
and sewage dome 2 (S-2C) in relation to the percent
nitrate plus nitrite nitrogen of the total nitrogen in
the influent. . . . . ... . . . ..... 69

3-8 Percent nitrate plus nitrite nitrogen in the treated
sewage influent vs. percent nitrate plus nitrite
nitrogen in the centers of sewage dome 1 (S-1C) and
sewage dome 2 (S-2C). . . . ... .. . . . 70

3-9 Mean total phosphorus levels in the surface waters of
control and experimental domes. Each point is the
mean of the one center and one or two edge stations
for each dome, except Austin Cary where only the center
station is plotted. (G-1 is the groundwater control
dome, S-1 is sewage dome 1, and S-2 is sewage dome 2.). 76

3-10 Cumulative nitrate plus nitrite nitrogen in the
leachates of sediment leaching columns receiving
groundwater, treated sewage, and treated sewage with
added nitrate plus phosphate eluants. . . . . 85

3-11 Time course of N20 buildup following acetylene blockage
in sediment leaching columns. The sediments were taken
from the groundwater control dome and had received the
eluants listed above for 8 months prior to the addition
of 0.1 atm C2H2 . . . . . . . . . .. 88








Figure Page

3-12 Cumulative ammonium nitrogen in the leachates of
sediment leaching columns receiving treated sewage
and groundwater eluants. Arrows denote when eluant
concentration of ammonium decreased (in sewage treated
columns) or increased (in groundwater treated columns). 91

3-13 Cumulative ammonium nitrogen in the leachates of
sediment leaching columns receiving treated sewage
with added nitrate plus phosphate as the eluant.
Arrow denotes when eluant concentration of ammonium
decreased . . . . . . . . . . 92

3-14 Cumulative total phosphorus in the leachates of
sediment leaching columns receiving groundwater,
treated sewage, and treated sewage with added nitrate
plus phosphate eluants. . . . . . . . ... 99

4-1 Major ions, silica and conductivity in seawater and
the natural waters of Austin Cary cypress dome. .... .103

4-2 Monthly variations in the depth of the standing
water at the center of Austin Cary cypress dome .... .105

4-3 Monthly variations in the conductivity for Austin
Cary cypress dome . . ... . . . . ..... 106

4-4 The effect of H2C03* on the free, bound and total
acidity of the surface water from Austin Cary cypress
dome. The unpurged curve represents the presence of
H2C03*. The purged curve represents an aliquot from
the same sample from which the H2C03* has been removed.
The symbols Pf, Pb, and PT represent, respectively,
the concentration of free protons, bound protons, and
total protons (in micro-equivalents per liter); Pb is
determined by difference, PT Pf. The symbil %Pf
represents the percentage of total protons that are
free. Sample collected on March 15, 1979 . . ... 110

4-5 The relationship of Austin Cary cypress dome to
other world surface waters with respect to the
controlling mechanisms of their chemical compositions
according to Gibbs' model . . . . . . ... .114

4-6 Nitrogen, phosphorus, and aluminum concentrations in
the natural waters of Austin Cary cypress dome. .... .117

4-7 Equilibrium solubility domain of amorphous Fe(OH)3(s)
showing the Fe hydrolysis and Fe-P04 complexes in the
surface water of Austin Cary cypress dome. The shaded
area represents the range of "soluble" total iron (FeT)
measured. . . . . . . . . .. ...... 122








Figure Page

4-8 Monthly variations in the silica concentrations
for Austin Cary cypress dome standing water
during a 1-year period . . . . . . . .. 124

4-9 Correlation of total organic carbon with color
for Austin Cary cypress dome. . . . . . . ... 128

4-10 Correlation of iron with total organic carbon
for Austin Cary cypress dome. . . . . . . ... 129

4-11 Correlation of iron with color for the standing
water of Austin Cary cypress dome . . . . .... 130

4-12 Correlation of aluminum with total organic carbon
for Austin Cary cypress dome. . . . . . . ... 131

4-13 Correlation of aluminum with color for Austin
Cary cypress dome . . . . . . . . .132

4-14 Monthly variations in the soluble reactive
phosphorus and organic phosphorus concentrations
for Austin Cary cypress dome standing water ...... 134

4-15 Monthly variations in the ammonium nitrogen and
nitrate plus nitrite nitrogen concentrations for
Austin Cary cypress dome standing water . . . ... 138

4-16 Monthly variations in the organic nitrogen
concentrations for Austin Cary cypress dome
standing water. . . . . . . . . ... .. 140

5-1 The decomposition curves of cypress leaf litter
for sewage dome 2 and Austin Cary natural dome
showing that decomposition is not accurately repre-
sented by a simple exponential decay model of the
form y = e-kt.

5-2 Decomposition values (X S.E., n = 5) from litter
bags at Austin Cary natural dome and sewage dome
2, and decomposition curves predicted from a two-
compartment decay model of the form y = pe-kit +
(1-p)e-k2t . . . . . . .. . . . .... 145

5-3 Predicted course of decomposition for duckweed based
either on the separation of the observed data into
fast and slow components (two-compartment model) or
on fitting the observed data to a simple exponential
model of the form y = e-kt (one-compartment model . . 148









Figure rage

5-4 Values used to simulate model of litter accumula-
tion on the swamp floors of sewage dome 2 and
Austin Cary natural dome using the nonlinear two-
compartment decomposition model (y = pe-kit +
(1-p)e-k2t). Initial conditions for the amount of
slow decomposing cypress litter was 20.3 kg OM/m2
for both domes; all other stocks were initialized
at zero. See Appendix 1 for calculations, assump-
tions, and references used in evaluating this
diagram . . . . . .... . . . . 149

5-5 Percent organic matter in cores taken at various
distances from the centers of Austin Cary natural
dome and sewage dome 2. . . . . .... . . 153

5-6 Simulated change in organic matter on floor of
cypress domes over 10 years in the undisturbed
dome in the Austin Cary Forest and in a sewage-
enriched dome (sewage dome 2) . . . ........ . . 155

6-1 Generalized model of the nitrogen cycle For a
swamp . . . . . . . . . . . . 158

6-2 Systems model of the nitrogen cycle showing the
major environmental factors controlling transfor-
mations. Symbols are from Odum (1971). ....... 159

6-3 The nitrogen cycle presented as a simple series
energy flow .. . . ....... ........ 161

6-4 Seasonal variation in the nitrogen fixation rates
(C2H2) by the surface layer of peat from Austin
Cary natural dome and sewage dome 2 from August 12,
1978 to August 12, 1979. Each point is the mean of
three to six replicates . . . . . . . . .174

6-5 Acetylene reduction activity by five peat samples
from sewage dome 2 during November 2-3, 1978.
Incubations were initially aerobic and performed
within one hour of sampling under 0.12 to 0.17 atm
C2H2 at 170C. . . ... . . . ..... 176

6-6 Acetylene reduction in peat from Austin Cary natural
dome. Each depth interval is the mean of three
subsamples from one core. The surface sample is the
mean of six samples . . . .. .. .... .177









Figure Page

6-7 Exchanges of nitrogen in Taxodium distichum var.
nutans leaves during decomposition in the standing
waters of Austin Cary natural dome and sewage dome
2. Each point is the percent remaining of the
amount in the original bag and is a mean of five
replicate bags. The mean nitrogen concentrations
at to (as percent dry wt) were 0.81 percent and
1.50 percent for Austin Cary natural dome and
sewage dome 2, respectively . . . . . .... 179

6-8 Acetylene reduction activity (ARA) associated
with excised roots of pond cypress (Taxodium
districhun var. nutans), black gum (Nyssa sylvatica
var. biflora), and buttonbush (Cephalanthus
occidentalis). The aerobic incubations were
pre-incubated 23 h before adding C2H2. (Nyssa
biflora should be properly listed as Nyssa
sylvatica var. biflora.). . . . . . . . 186

6-9 Acetylene reduction associated with excised roots
of Nyssa sylvatica var. biflora (black gum) and
surrounding peat from August 30 to September 2,
1978. Incubations were initially aerobic under
0.1 atmosphere C2H2 in the dark and at 24C with
9 percent (vol) de-ionized water. Roots were
excised, washed in de-ionized water, and incubated
within 2 hours of collection from Austin Cary natural
dome. Each data point represents the mean of three
replicate samples. (Nyssa biflora should be
properly listed as Nyssa sylvatica var. biflora.) . . 188

6-10 Time course of acetylene reduction associated with
excised roots of Taxodium distichum var nutans from
April 5 to 9, 1979. Incubations were initially
aerobic under 0.1 atmosphere C2H2 in the dark and at
240C with 7 percent (vol) surface water. Roots were
excised, washed in the de-ionized water and incubated
within 2 hours of collection from Austin Cary natural
dome and sewage dome 2. Each data point represents
the mean of four or five replicate samples. . . .. 189

6-11 Time course of acetylene reduction activity
associated with excised roots of pond cypress
(Taxodium distichum var. nutans) from September 22
to 26, 1979. All roots were excised and surface
sterilized with a 1 or 10 percent of chloramine-T
or immersed in sterile phosphate buffer (pH 7.0) for
1.5 hours within 2 hours after removal from Austin Cary
natural dome. Incubations were initially aerobic under
0.1 atmosphere C2H2 in the dark at 24C with 36 percent
(vol) in situ water. Each point represents the mean
of five replicate samples . . . . . . . .191
xvii








Figure Page

6-12 Exchange of nitrogen in Taxodium distichum
var. nutans leaves during decomposition in the
standing waters of Austin Cary natural dome and
sewage dome 2. Each point represents a mean of
five values. The values plotted are percentages
of the concentrations present at to if there had
been no loss of dry weight.... .... . . .197

6-13 Dry weight loss of Taxodium distichum var.
nutans leaves in the standing waters of Austin
Cary natural dome and sewage dome 2 . . . . .. 198

6-14 Production of N20 by submerged peat incubated
in a He atmosphere with 0.1 atm C2H2. Curve 1,
Austin Cary dome peat, nitrate, and C2H2; curve
2, Austin Cary dome peat, nitrate, glucose, and
C2H2; curve 3, Austin Cary dome peat, nitrate,
glucose, NaHCO3, and C2H2; curve 4, Austin Cary
dome peat nitrate, NaHC03, and C2H2; curve 5,
Austin Cary dome peat, HgCl2, N20, and C2H2; curve
6, sewage dome 2 peat, nitrate, and C2H2. Each
data point represents the mean of three replicate
flasks, except for curve 5 where each data point
is the average of duplicate flasks. . . . . ... 202

6-15 Nitrification in surface water in Austin Cary
natural dome. Each data point is the mean of
duplicate bottles. The solid lines represent
nitrate plus nitrite nitrogen concentrations and
the dashed lines represent the ammonium nitrogen
concentrations. ..... . . . . . . 211

7-1 Nitrogen mass balance for sewage dome 2. All
numbers are in g/m2-yr and are the averages of a
three-year period (1975-1977).. . . . . . .. 221

7-2 Phosphorus mass balance for sewage dome 2. All
numbers are in g/m2-yr and are the averages of a
three-year period (197501977).. . . . . . .. 222

7-3 Phosphorus mass balance for Austin Cary natural dome.
All numbers are in g/m2-yr and are the averages of
either a four or five-year period (1975-1978 or 1979) 224

7-4 Nitrogen mass balance for Austin Cary natural dome.
All numbers are in g/m2-yr and are the averages of
either a four or five-year period (1975-1978 or 1979) .225

7-5 Fluctuations in the surface water level of sewage dome
2 during the study period. Sewage loading was
initiated in December 1974. . . . . . . 234


xviii








Figure


Page


7-6 Water level fluctuations in the surface waters of
the center of Austin Cary natural dome from
1974 to 1979) . . . . . . . .. . . 236

7-7 Areal distribution of sediment nitrogen measured in
sewage dome 1 (S-1) and groundwater control dome (G-1).
The average nitrogen storage in the sediments was
852 g/m2 and 674 g/m2 for sewage dome 1 and ground-
water control dome, respectively. . . . .... 242

7-8 Areal distribution of sediment nitrogen measured in
Austin Cary natural dome. The average nitrogen storage
in the sediments was 604 g/m2 ........... . 243

A-1 Analog program for simulating the organic matter
accumulation model on the swamp floors of a natural
and sewage-enriched cypress dome. (S-2 and A.C. denote
sewage dome 2 and Austin Cary natural dome,
respectively.). .......... . . . . .. 261














Abstract of Dissertation Presented to the Graduate Council
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy


THE EFFECTS OF SECONDARY SEWAGE EFFLUENT ON THE WATER QUALITY,
NUTRIENT CYCLES AND MASS BALANCES, AND ACCUMULATION OF SOIL
ORGANIC MATTER IN CYPRESS DOMES

By

Forrest Edward Dierberg

August 1980

Chairman: Patrick L. Drezonik
Major Department: Environmental Engineering Sciences

Considerable alteration in the nitrogen cycle of natural cypress

domes occurs when they are used for treated sewage disposal. Both

the rates of the major nitrogen transformation processes and the

controlling environmental factors are significantly changed by input

of secondary sewage effluent. Nitrogen and phosphorus are conserved

in both the natural and sewage-enriched domes because nitrification is

inhibited, rates of mineralization are low, and significant surface

overflows do not occur. Although most sites within natural cypress

domes do not fix significant amounts of nitrogen, excised, non-nodulated

roots of the dominant woody vegetation of cypress swamps were found to

be capable of low rates of fixation, as measured by the acetylene

reduction assay. This finding opens a new area of research in the

cycling of nitrogen in cypress wetlands.

The capability of cypress domes to act as efficient nutrient

traps has been demonstrated for a natural and sewage-enriched cypress









dome. Mass balance models indicated that 87 percent of the nitrogen

and 92 percent of the phosphorus loadings were retained within a

cypress dome receiving secondary sewage effluent, removal efficiencies

that are among the highest reported for any wetland ecosystem receiv-

ing treated sewage. Thus, cypress domes seem to be effective natural

tertiary treatment systems. Cypress tree uptake accounted for only

1 percent of the phosphorus and 24 percent of the nitrogen inputs in

the sewage-receiving dome, leaving the majority stored in the sedi-

ments. For a natural dome, 67 percent of the phosphorus and 27-58

percent of the nitrogen remaining in the dome were taken up and stored

in cypress trees. Field data and laboratory investigations demon-

strated that denitrification was a major nitrogen sink in both natural

and sewage-enriched domes.

Bulk precipitation was the most important factor in supplying new

minerals and nutrients (except nitrogen) to the natural cypress dome.

Potassium, phosphate, ammonium, and nitrate plus nitrite had lower

levels in the surface water than in throughfall, indicating that these

elements are important in the biological and chemical processes of

these domes.

Analyses of standing waters of natural and sewage-enriched cypress

domes near Gainesville, Florida, over a 4.5-year period showed that

discharge of secondary sewage effluent altered the soft, acid water

found in natural domes to a neutral, moderately hard condition.

Furthermore, the absence of dissolved oxygen, high levels of phsophorus,

nitrogen, biochemical oxygen demand, and the presence of hydrogen

sulfide mean that treated sewage effluent has a substantial impact on

water quality. Standing water quality following the cessation of









sewage pumping did not return to the same quality as found for the

natural dome within 20 months. iater samples from shallow wells,

ceramic soil moisture tubes, and laboratory percolation columns indi-

cated that the underlying organic matter and sands were serving as an

effective barrier to the transport of sewage pollutants to the shallow

aquifer immediately below. The largest percentage removals for all

measured water quality parameters through the entire conventional

treatment plant/dome system occurred between the surface and ground-

water stations.

Cypress leaves decomposed more rapidly in a sewage-enriched

cypress dome than in an undisturbed cypress dome. A model incorpor-

ating both labile and refractory components of cypress leaves was

found to produce a better fit to decomposition data than a simple

exponential decay model. Simulated rates of litterfall and decompo-

sition under natural conditions and with sewage enrichment indicated

that duckweed productivity generated by sewage addition will have

minimum effect on the storage capacity of dome basins.


xxii














CHAPTER ONE
INTRODUCTION

Forested wetlands have received little scientific investiga-

tion in the past because of the low recreational and economic values

placed on them by man. Only recently have they been recognized as

valuable resources because of their important roles in water conser-

vation and maintenance of water quality. As the true costs of the

1983 "zero discharge" requirement of the 1972 Federal Water Pollution

Control Act have become apparent in recent years (estimated $594

billion by the National Commission on Water Quality), wetland dispos-

al of treated sewage effluent has received increased attention as a

possible low-cost alternative to conventional tertiary treatment

methods. Wetland disposal may have the further advantage of simul-

taneous recharge of groundwater aquifers. However, the efficacy of

using forested wetlands as sites for long-term treated sewage dis-

posal has yet to be completely demonstrated and many questions in-

volving the long term effects of treated sewage disposal on the swamp

ecosystem still remain unanswered. For example, the quantitative

aspects of nutrient mass balances are poorly understood in forested

wetlands. Only a prolonged research effort by investigators repre-

senting many disciplines will adequately answer all these questions.

Some answers to these questions have been reached in an inter-

disciplinary research effort at the University of Florida dealing

with the following question: Can cypress domes process









secondary-treated sewage effluent to a tertiary state in an economic

and efficient manner?

The mass or materials balance approach is useful in evaluating

the efficacy of using wetlands as treatment systems for nitrogen and

phosphorus removal in secondary-treated effluent. The mass balance

concept has been used in solving problems involving the cycling of

essential elements (nitrogen, phosphorus, sulfur, and carbon) on

global (e.g., SCOPE 1976; CAST 1976), regional (e.g., Messer 1978),

and ecosystem (e.g., Bormann et al. 1977) levels.

For elements that have complex physico-chemical interactions and

transformations, such as nitrogen, erroneous or incomplete data lead

to large uncertainties in the values for some of the reservoirs or

flows. Because the conclusions based on a mass balance model can

only be as precise, accurate and sensitive as the data from which the

model was constructed, the completeness and quality of the data are

of paramount importance in producing a model that has meaningful rela-

tionships among its system components. Unfortunately, the manpower

and analytical facilities required to achieve a complete and accurate

mass balance model for nitrogen have been too great to be undertaken

within budgetary limitations. Because of these constraints, nitrogen

mass balance models in wetland ecosystems are often incomplete.

Qualitative information on the transformations, fluxes, and

storage of nitrogen and phosphorus is abundant. Complete and de-

tailed reviews have considered nitrogen and phosphorus cycling in

wetland and aquatic systems (Erickson 1978; Good et al. 1978; Keeney

1973; Ponnamperuma 1972; Syers et al. 1973; Wetzel 1975).









Wetlands have long been recognized as nutrient traps. Van der

Valk et al. (1978) reviewed 17 studies on various types of wetlands.

Phosphorus was removed in all 16 studies that measured phosphorus,

and 12 of the 14 studies involving nitrogen reported at least season-

al removal. Two studies found wetlands to act as nitrogen sources.

Studies on palustrine wetlands (i.e., nontidal wetlands that

are not confined by channels and are not marginal to lakes) have in-

dicated nitrogen and phosphorus removals during the entire year (Boyt

et al. 1977; Fetter et al. 1978; Hermann 1979; Nessel 1978; Richardson

et al. 1978; van der Valk et al. 1978). Removal efficiencies in

northern marshes decline in the spring and fall when high hydraulic

loadings wash out some of the nutrients assimilated during the pre-

vious growing season and mineralized during the previous fall (Lee

et al. 1975; Spangler et al. 1977). Only one study reported that

assimilative capacity of a palustrine wetland (Everglades) was ex-

ceeded by the discharge of high nutrient effluent (Steward and Ornes

1975).

The capability of wetlands to trap nutrients has resulted in

recent studies aimed at exploring how they respond to the addition of

wastewater (Boyt et al. 1977; Odum et al. 1975; Sloey et al. 1978;

Richardson et al. 1978; Whigham and Simpson 1976; Zoltek et al. 1979).

Sloey et al. (1978) point out that palustrine wetlands are more

amenable to management for wastewater treatment than other major wet-

lands (tidal, riverine, and lacustrine) because palustrine wetlands

are hydraulically isolated from open surface water and hydraulic resi-

dence times are high.









Recent reviews on nutrient dynamics in wetlands (van der Valk

et al. 1978; Whigham and Bayley 1978) have stressed the absence of

studies that assess the nutrient removal efficiency of wetlands on an

annual, areal basis. In fact, few studies have quantified any aspect

of nutrient cycling within wetlands. For example, only 8 of the 21

papers reviewed by Whigham and Bayley (1978) contain any input or out-

put data. Prentki et al. (1978), Deghi (1977), and Zoltek et al.

(1979) have provided partial mass balance models for nutrients in

wetlands.

The specific questions which my research addresses are:

1) How efficient are cypress domes in removing the pollutant

loads in secondarily-treated discharge?

2) How long can chemical and microbial processes effectively

treat secondarily-treated sewage to a tertiary state?

3) What are the chemical characteristics of surface and ground-

waters in a natural cypress dome and how are they altered by sewage

disposal?

4) To what extent and how fast can the major water quality

parameters revert back to natural levels once sewage disposal has

been discontinued?

5) How does sewage disposal alter the processes involved in the

nitrogen cycle of a natural dome?

6) What are the nitrogen and phosphorus budgets of sewage-

enriched and natural cypress domes?

7) To what extent does treated sewage disposal increase the rate

of organic accumulation on the swamp floor, thereby reducing the

hydraulic capacity of the dome basin?














CHAPTER TWO
AREAS OF INVESTIGATION, SAMPLING PROCEDURES,
AND ANALYTICAL METHODS

Site Description

The main study site consists of three cypress domes located

about 5 km north of Gainesville, Florida, on a large pine plantation

owned by Owens-Illinois, Inc. (Figure 2-1).

A "package treatment plant" serving a 155-unit mobile home park

adjacent to the site supplied secondarily-treated sewage effluent to

sewage dome 1 (0.51 ha) and sewage dome 2 (1.05 ha), respectively

(Figure 2-2). Pumping was initiated in Ilarch 1974 to sewage dome 1

and December 1974 to sewage dome 2. The sewage plant is an extended

aeration waste treatment facility which is currently treating about

95 m3/day (25,000 GPD), 83 percent of its design capacity of 114

m3/day (30,000 GPD). The treated effluent is then discharged into

an oxidation pond.

During the period from March 1974 to March 1975, the sewage

pumped to the cypress domes came directly from the package treatment

plant, which was not operating efficiently. Hydraulic loadings were

as low as 0 cm/wk (June 1974) and as high as 14 cm/wk (August 1974).

Sludge occasionally was pumped into the domes. After March 1975, more

even and constant sewage applications (2.5 cm/wk with no sludge) were

obtained using effluent that had been in the oxidation pond for an

average detention time of 10 days. The influent pipe within the


























































Figure 2-1. Locations of the two major study sites in Alachua County.


























































































































U
W
C O
W
N 4~
5 1
yO
y10








oxidation pond was relocated in March 1976 to a point closer to the

treatment plant.

A combination of high sewage application rates, heavy rainfall,

and abnormally high surface runoff during summer, 1974, caused over-

flow from sewage dome 1. A weir was constructed on the west side of

the dome to maintain the standing water at a more constant level and

to allow the overflow to be measured and sampled.

A third dome, the groundwater control dome (0.70 ha) at the

Owens-Illinois site received groundwater from a deep well (n50 m) ac-

cording to the same schedule and loading rate as sewage dome 1 begin-

ning in March, 1974. It served as a hydrologic control, separating

the response of acidic cypress domes to application of hard, alkaline

groundwater, from the effects of sewage pollutants (nutrients and

organic matter).

Two of the three domes, the groundwater control dome and sewage

dome 1, were burned extensively in an unintentional forest fire on

December 4, 1973, while the third dome, sewage dome 2, was burned

only along the southwest edge.

A larger dome (4.2 ha), located about 17 km northeast of the

Owens-Illinois site in the Austin Cary Memorial Forest (Figure 2-1),

served as a "natural" control whose water levels fluctuated accord-

ing to the normal hydroperiod. Activities connected with the research

project (well drilling, installation of a boardwalk, tower, equipment

shed, and various monitoring devices) have somewhat altered the

natural character of this dome.








Sampling Procedures

Standing Waters, Sewage, and Shallow Groundwaters

The standing waters, sewage, and shallow groundwaters on the

Owens-Illinois site and the standing waters of the Austin Cary dome

have been routinely monitored for major cations and anions, nutrients,

and other water quality parameters since March 1974 (Table 2-1).

Samples were collected on a monthly basis until December 1976, fol-

lowed by quarterly sampling until May 1979, from the Owens-Illinois

stations listed in Table 2-2. Beginning in April 1978, monthly

sampling of Austin Cary dome surface waters was resumed until July

1979.



Table 2-1. List of physical and chemical parameters for which
analyses were performed.


Basic Water Chemistry Nutrient Forms Major Cations
and Quality and Anions


Alkalinity NH4 -N Ca+2

pH (NO3 + NO )-N Mg+2

Color Organic N Na+

Dissolved oxygen PO4-P K+

Turbidity Total P A1+3

Specific conductance F

BOD5 Cl
-2
Inorganic Carbon SO4

Organic Carbon

Sulfide









Table 2-2. Schedule for routine sampling

No.
Site samples Descriptions
Samples


Sewage


Groundwater


Wells 22, 28, 33, and 38


Austin Cary natural dome


Groundwater control dome


Well surrounding ground-
water control dome

Sewage dome 1


Wells inside and sur-
rounding sewage dome 1

Sewage dome 2


Wells surrounding sewage
sewage dome 2


2 Treated effluent, oxidation
pond effluent

1 Deep well supplying ground-
water control dome

4 Background for shallow water
table aquifer

1 Standing water, Austin Cary
dome center

2 Standing water; center,
30 m west

1 Well 30


3 Standing water; center,
30 m east, weir overflow

3 Wells 4A, 8A, and 19


3 Standing water; center,
40 m north, 30 m south

4 Wells B-3, B-5, B-7, and B-9


Beginning in March 1976, the frequency of analysis was reduced

for parameters that showed constant or predictable trends. At that

time, monthly hydrogen sulfide analyses on the surface waters were

added and the frequency of measurements of pH, color, specific con-

ductance, and major cations was reduced for both surface and ground-

water stations from a monthly to a quarterly basis. Alkalinity and

sulfate were analyzed semi-annually instead of quarterly for all









surface and groundwater stations. All other parameters were measured

quarterly instead of monthly at the groundwater stations. Monthly

analysis of all parameters in the standing waters of Austin Cary were

resumed in April 1978 and continued to July 1979.

In addition to the regularly scheduled sampling stations listed

in Table 2-2, wells 20, 27, 29, 31, 34, 35, 36, 37, and 38 near the

groundwater control dome; wells 3A, 5A, 6A, 7A, 11A, and 9A inside

sewage dome 1; wells B-2, B-4, B-6, B-8, B-10, B-11, and B-12 at

sewage dome 2; and wells 1, 4, 12, 14, 18, and 21 surrounding sewage

dome 1 were sampled occasionally, especially in the early years of the

monitoring program (Figure 2-2). All wells are shallow (3-6 m deep)

and they just penetrate a hardpan stratum.

In order to provide a basis for comparing the groundwater quality

among the various groups of wells and to assess the removal of sewage

pollutants from nearby sewage domes, the well data were composite

into five groups: 1) B-1 through B-12 surrounding sewage dome 2

(B-wells); 2) wells 1, 4, 12, 14, 18, 19, 20, and 21 surrounding

sewage dome 1 (S-1 wells); 3) wells 3A, 4A, 5A, 6A, 7A, 8A, 9A, and

11A located within sewage dome 1 (A wells); 4) wells 29 through 31

surrounding the groundwater control dome (GC wells); and 5) wells 22,

27, 28, 33, 34, 35, 36, 37, which are distant from any of the experi-

mental or control cypress domes and can be considered representative

of the natural groundwaters of the area. Wells 22 and 28 on the east

sides of sewage dome 1 and groundwater control dome, respectively,

were not included in the sewage dome 1 and groundwater control dome

well composites, since the groundwater flow around these domes is in

a westerly direction (Heimburg 1976).









The procedure for sampling wells involved pumping each well dry

(or removing at least 2 liters) two or three days before sampling so

fresh percolate could be collected. Samples were collected with a

hand vacuum pump (Nalgene) by drawing water through s inch i.d. Tygon

tubing that was custom-fitted to each well (down to the perforated

zone, 0.3-0.6 m above the bottom of the casing) (Figure 2-3). The

first liter of water drawn was discarded to clean the tubing of con-

taminants. Samples were then collected directly in acid-washed

125-ml polyethylene bottles for major cations, specific conductance,

and chloride analyses. Samples were also collected into acid-washed

500-ml polyethylene bottles for nutrient and other water quality

analyses. One-half milliliter saturated HgC12 was added to the 500-ml

polyethylene bottle, which was placed on ice in the field.

Surface water "grab" samples were taken with a 1-liter poly-

ethylene bottle for BOD5 analysis, and two glass 300-ml BOD bottles,

one each for H2S and dissolved oxygen determinations. The last two

samples were collected using a BOD sampler (Wildco) in order to in-

sure against the introduction of oxygen during sampling. The bot-

tles containing samples for sulfide and BOD5 analyses were placed on

ice, while the bottles containing samples for dissolved oxygen deter-

minations were fixed in the field by addition of ninS04 and alkali

azide iodide. Surface water "grab" samples were also collected in

125-ml and 500-ml polyethylene bottles. The parameters measured and

the methods of preservation were the same as described previously

for the well samples.

Upon return to the laboratory (usually within 4 hours of collec-

tion), nutrient samples containing HgCl2 preservative were stored at















WELL CASING ---


1/4" SAMPLE TUBING VACUUM


SAMPLE
BOTTLE











GROUND LEVEL


Figure 2-3. Sampling equipment and technique for sampling the shallow
groundwaters.








4C. Sulfide, BOD5, dissolved oxygen, and pH were determined within

24 hours of sampling. All other parameters except sulfate, fluoride,

chloride and the major cations were analyzed within two weeks.

Runoff

From August 2, 1976, to January 20, 1978, 10 rainfall events were

sampled at stations near sewage domes 1 and 2 (Figure 2-2) to deter-

mine N and P loadings from surface runoff. Two additional rainfall

events were sampled at three stations at the Austin Cary site on

December 25, 1977, and January 20, 1978. Samples were collected at

intervals ranging from 15 min to 1 hr, depending on the time elapsed

since initial flow into the domes.

Bulk Precipitation and Throughfall

Precipitation was collected weekly from April 18, 1978, to April

19, 1979, at stations above and below tree canopy in the Austin Cary

dome. The station above the dome was situated atop the tower at the

center of the dome (27 m high and located above the tree crowns),

while the station below the dome canopy was located near the board-

walk 20 m northeast of the dome center (Figure 2-4).

Each collector consisted of a polypropylene funnel (surface open-

ing of 552 cm2) fitted with a teflon wool plug (Figure 2-5). A vapor

barrier was provided by a loop in the y.gor tubing, thus preventing

ammonia loss or gain from the atmosphere and evaporation from the

reservoir. An overflow tube allowed excess water to drain during

large precipitation events (>7.6 cm rain).

The funnels were not replaced, in order to collect the dry fall-

out deposited on them since the last rain event, but containers were

replaced after collecting samples. Litter accumulated in the funnel























C r-


01





EC

( n
Io



4-







Idu
4r-





E u



0



*'r-
4-'

Id





C 0.
0 .-





o0



U'






S4-1
u S>

30I
9:0 0
. 4- .C

UL

Cr- 0d
(o


4-'








L(1
<1I-


ulON















POLYETHYLENE
FUNNEL


-OU--VAPOR BARRIER TRAP

TWIST-TIE TO
FORM LOOP

TYGON TUBING












POLYETHYLENE
RESERVOIR
VAPOR
S^BARRIER TRAP


Figure 2-5. Precipitation collector.









was discarded. The volume collected during each sampling time was

measured, except when precipitation events produced more water than

the container could hold. Data from the University of Florida Beef

Research Unit located 8 km southwest of the Austin Cary dome were

used to estimate the amount of rainfall.

Plant Biomass

Yearly measurements were made of the diameter at breast height

(DBH) for 100 trees in each of the three study domes at the Owens-

Illinois site and 200 trees in Austin Cary dome. Diameter at breast

height was measured at 1.37 m above ground surface or above severe

butt swell. In addition, yearly samples of foliage, branches, and

stems were taken from eight cypress trees in each dome for determina-

tion of nitrogen and phosphorus content beginning in September 1973

and ending in July 1977.

Tree cores were obtained with an increment borer. Foliage and

branches were sampled with a 16-gauge shotgun (No. 2 and 4 magnum

load). The samples were cut into small pieces in the field and stored

in paper bags until dried at 800C and ground in a Wiley mill to pass

a No. 20 mesh screen.

Peat

A 4 cm dii) mter a luminuim ipe with a beveled tip was used to

obtain cores from the four domes during May 1977. The cores were

extruded in the field and segmented at 5 cm intervals. The segments

were put into polypropylene bags and frozen until the time when dry

and ash weights and nitrogen content were determined.








Methods

Hater Quality Parameters

Analysis of major cations was performed using a Varian Techtron

Model 1200 Atomic Absorption Spectrophotometer with the instrument

settings recommended by the manufacturer. Sample atomization was by

an air/acetylene flame. One milliliter of a La-HC1 solution (29 g

La203 and 250 ml concentrated HC1 diluted to 500 ml) was added to each

10 ml of a Ca and Mg sample. AutoAnalyzer procedures were used to

determine nitrate plus nitrite (cadmium reduction method), ammonium

(indophenol method), Kjeldahl nitrogen (semi-micro digestion followed

by determination of ammonium), chloride (ferric thiocyanate method),

aluminum (eriochrome cyanine R method), sulfate (methylene blue method)

and silica (molybdenum blue method); procedures for each parameter were

obtained from U.S. EPA (1974) or APHA (1976). Soluble reactive phos-

phorus and total phosphorus (persulfate digestion) were determined

spectrophotometrically by the molybdenum blue method (APHA 1976). Sul-

fide analysis was by the method of Strickland and Parsons (1972), where

Lauth's violet formed from p-phenylenediamine is measured spectropho-

tometrically. Fluoride was measured by ion-selective electrode (APHA

1976), and pH by glass electrode. Dissolved organic and inorganic

carbon were analyzed using a Beckman Model 915 carbon analyzer.

Dissolved oxygen was determined by the azide modification of the

Winkler method. Five-day biochemical oxygen demand was determined

by the amount of oxygen lost after incubating for 5 days in the dark

at 200C (APHA 1976). Alkalinity was measured titrimetrically with

0.02 N H12SO4 as the titrant and methyl red-bromcresol green as the

end point indicator (APHA 1976). Total acidity (Austin Cary surface









water only) on He-purged and unpurged samples was determined by

titrating a 500 ml sample (closed to the atmosphere) with 0.00907 N

NaOH (standardized with potassium biphthalate) using a pH electrode

(Figure 2-6). Turbidity (Hach Model 2100 nephelometer), color (spec-

trophotometer), and specific conductance measurements followed APHA

(1976). Sulfate in samples from the Owens-Illinois site was deter-

mined turbidimetrically (APHA 1976).

Analytical problems were encountered with the organic-colored

surface waters. Analyses involving spectrophotometric methods were

particularly susceptible to positive interference from color present

in the samples. The extent of such interference depended on the con-

centration of the measured parameter, wavelength used, and pH of the

final reaction mixture. For the levels of color normally found in the

standing waters of Austin Cary (300 to 800 CPU), blank correction

procedures were instituted for the parameters (Table 2-3).

EPA reference samples were analyzed along with the samples for

calcium, magnesium, sodium, potassium, sulfate, chloride, fluoride,

Kjeldahl nitrogen, ammonium, nitrate plus nitrite, phosphate, total

phosphorus and BOD, and were consistently within 10 percent of the

stated concentration.

Nitrogen and Phosphoru' Removal Studies

Soil-solution studies

Soil-solution sampling tubes consisting of porous ceramic cups

attached to 3.8 cm i.d. PVC pipes were installed at three soil depths

(60, 120, and 180 cm) near the edges of the groundwater control dome

and sewage domes 1 and 2 (see Figure 22 for locations of soil tubes).

For the stations closest to the sewage domes, duplicate tubes were


































pH ELECTRODE







600 ml TALL FORM
BERZELIUS BEAKER












STIRRING BAR


Figure 2-6. Apparatus used in total acidity titrations.








Table 2-3. Parameters influenced by organic color and the blanking
procedures used to compensate for the interference.


Parameter Blanking Procedure


Aluminum Blank concentration obtained by adding 2
drops of a 10-3M EDTA solution to 2 mls of
sample diluted 1:10, thereby completing the
Al.
Chloride Absorbance obtained by substituting deion-
ized water for the mercuric thiocynate
reagent was subtracted from the sample
absorbance measured with all reagents added.
Nitrate plus nitrite Blank concentration obtained by deleting the
(only for samples with sulfanilimide from the 1 percent sulfanili-
color concentrations mide-0.1 percent N-(1-naphthyl) ethylene
>800 CPU) (i.e., diaminedihydrochloride (NNED-HC1) reagent
leachate from columns) was subtracted from the measured concentra-
tion.

Phosphate Blank concentration obtained by substi-
tuting deionized water for the ascorbic
acid in the mixed reagent was subtracted
from measured concentration.

Sulfate At low levels of sulfate, high levels of
organic color can interfere with the preci-
pitation of BaSO4 in the turbidimetric
method (APHA 1971) and with the quantita-
tive complexation of excess Ba+2 by methyl-
thymol blue in the automated colorimetric
method. Organic color for Austin Cary
standing waters was oxidized by adding
1 ml of a 30 percent reagent grade H202 to
100 ml of sample and then heating. Because
sulfate was an impurity in the H202, dis-
tilled water blanks also were heated with
1 ml H202. The sulfate level found in the
blanks were then subtracted from the concen-
tration measured in the samples. Concen-
trations obtained by this method may exceed
the true sulfate concentration in the sample
because of the oxidation of reduced organic
sulfur compounds. The magnitude of this
error is unknown, since reduced sulfur spec-
ies in the standing waters were not analyzed.

Sulfide Double beam spectrophotometer was used with
the reference cuvette containing sample
without FeCl3 reagent.








placed at each depth. The other stations had only one soil tube at

each depth. The ceramic cups were washed in 1:2 concentrated HNO3

and rinsed in demineralized water before installation in the field.

Soil solution was sampled by drawing a vacuum in the tubes and col-

lecting the sample 24 hours later. Any water that had accumulated

in the tubes before a vacuum was applied was discarded. Samples

were obtained in November and December of 1976 and January, May, and

August of 1977. Nutrient concentrations were determined by the same

procedures cited above.

Laboratory leaching studies

Six columns were filled to a depth of approximately 17 cm

(volume u200 cc) with surface sediments from the groundwater control

dome (Figure 2-7). The sediments consisted of 58 percent water. One

pair received deep groundwater (from the Floridan Aquifer) as the

eluant, another pair received treated sewage (from the oxidation pond)

as the eluant, and the remaining pair received the same treated sew-

age spiked with either 20 mg nitrate-N/L or 30 mg nitrate-N/L plus

13.1 mg P/L as orthophosphate as the eluant. Frozen 100 ml aliquots

of each of the above eluants were thawed and used whenever the eluant

volume within the columns approached the surface of the sediments.

All eluants were filtered through a Whatman no. 4 qualitative filter

before being applied to the columns. The columns were allowed to

drain freely in the dark at 24 C over a 21-month period, and 14 to

15 pore volumes of eluant were passed through the columns during this

time. The flow rates approximated percolation rates measured for

sewage in the field (0.3 to 0.9 cm/day) (Heimburg 1976). The filter

paper (Whatman no. 4) at the bottom of each column was periodically
















POLYETHYLENE BAG
FILLED WITH AIR


PO




ALUMINUM
FOIL


LYETHYLENE
REDUCING
CONNECTOR


JTS
'ER


SURFACE SEDIMEF
---- FROM GROUNDWA1
-_CONTROL DOME

---_ - -Z





.. ----- GLASS WOOL-
S-- FILTER PAPER


TYGON TUBING
/ (!/8"i.d.)



HYPODERMIC
-* NEEDLE

.RUBBER
SEPTUM


25-28
cm


16-19
cm


Figure 2-7. Setup for nutrient removal (left) and acetylene blockage
(right) experiments.








replaced to maintain consistent flow rates. The column effluent was

collected on every second or third day in 25 ml graduated cylinders,

which had 1 drop of saturated HgC12 added prior to collecting the

leachate. Successive sample collections were pooled into 50 or 100 ml

aliquots and frozen. A layer of eluant was maintained over the sedi-

ments at all times.

After leaching had proceeded for 8 months, the columns (Figure

2-7) were rendered gas-tight, and the build-up of N20 in the head-

space with and without 0.1 atm of C2H2 was measured by injecting

500 p1 of headspace gas into a Tracor 550 gas chromatograph equipped

with a 63Ni electron capture detector. The detector was operated at

3500C in pulsed mode with an argon-methane (95:5) carrier gas. A

1.9 m column of Poropak Q operated at 550C was used to separate N20

from the other gases.

Oxidation reduction potential redoxx potential) was measured

before and after the acetylene blockage experiment with a shiny

platinum electrode positioned a few centimeters above the surface

sediments. A saturated calomel electrode was used as reference elec-

trode, and an Orion 401 ion meter served as a potentiometer. Cali-

bration of electrodes and potentiometer was made against a Fe+2/Fe+3

standard solution (Light 1972). Adjustments were made in the measured

potentials to a standard hydrogen reference electrode (Light 1972) at

pH 7 (Patrick and Mahapatra 1968).

Percent dry weight and specific gravity (i.e., dry weight den-

sity) were determined by filling a 14 or 19 cm3 vial with sediment

from the 0-6 cm, 6-12 cm, and 12 cm-bottom depth intervals for each

column. These were weighed and allowed to dry overnight at 105 C and








then reweighed. Percent volatile solids was also determined on these

samples by ashing overnight at 5500C and then reweighing.

Total ammonium (free and exchangeable) associated with the sedi-

ments was measured by shaking 4 mg (wet wt) of sediment from the 0-1

cm, 6-7 cm, 12-13 cm, and terminal cm depths for 24 h in 100 ml 2 M

KC1, followed by filtering through a 934 AH Whatman glass fiber fil-

ter. Ammonium concentration was measured on the AutoAnalyzer as

previously described, except ammonium standards were made up in

2 M KCl instead of distilled water.

The mass of NH4 -N (in mg) in each 6 cm interval of each column

was calculated using the specific gravity of sediments, the volume

occupied by a 6 cm length column, and the average mg NH4 -N per

gram dry wt of sediments before adding three intervals per column in

order to arrive at the total amount for the column.

In addition, total nitrogen by the micro-Kjeldahl method was

determined on the 0-6 cm, 6-12 cm, and 12 to terminal cm segments of

the sediments after leaching and on the entire sediment before

leaching. The same calculation as described above for determining

the mass of NH4 -N was used to obtain the mass of total N (in mg)

in each 6 cm interval for each column before adding the three inter-

vals per column in order to arrive at the total amount for the column.

Cypress Leaf Decomposition

Freshly fallen cypress leaves were collected from both sewage

dome 2 and the Austin Cary natural dome from November 6-10, 1977.

Fallen litter was harvested from cleared surfaces on the boardwalks,

platforms, and utility shed roofs on alternate days. The leaves

were stored in paper bags at room temperature until January 1, 1978.









Then, between 30 and 45 g fresh weight (nearest 0.1 g) were enclosed

in 2 mm x 2 mm mesh fiberglass screen bags. The bags were stapled

along the sides and the top at 5 cm intervals which left gaps large

enough for most invertebrates to enter, yet prevented loss of the

plant material.

On January 1, 1978, 40 bags containing litter from the natural

dome were placed in the center of that dome in one of the deepest

spots. Forty bags containing litter from sewage dome 2 were

placed near the center of sewage dome 2 but away from the turbu-

lence associated with the effluent. Litter bags were not placed at

the edges of either dome since Deghi (1977) found no significant dif-

ferences in the decomposition rates of cypress leaf litter between

center and edge sites.

In addition, five bags of cypress litter from each of the two

domes were carried to the field and then immediately returned for

determination of dry-wet weight ratios. These ratios were subse-

quently used to estimate the amount of dry weight originally present

in the bags.

Litter bags were collected in groups of five from each site after

decomposition had proceeded for 15, 29, 58, 114, 205, 297, 390, and

570 days. Their contents were removed within 24 hrs of collection,

dry weights were determined after drying at 670C for at least five

days, and percent loss of dry weight for each bag was calculated.

Total nitrogen and carbon were calculated as follows:

percent total N or C remaining =

100 x final dry wt x final N or C concentration
initial dry wt x initial N or C concentration (1)








Decomposition constants characterizing cypress leaf decomposi-

tion were calculated using a linearized version of the standard ex-

ponential decay model:

y = e-kt, (2)

where y is the fraction remaining of the original amount of litter at

time, t, k is the decomposition constant, and e is the base of the

natural logarithm.

Model of Organic Matter Accumulation on the Swamp Floor

The data obtained from the cypress decomposition study described

above were combined with other available data to model the effect of

secondary sewage effluent on the accumulation of organic matter in

cypress domes.

Two models describing organic matter accumulation were formu-

lated: one for the natural cypress dome, in which cypress trees pro-

vide the bulk of the litter, and one for the sewage dome, in which

duckweed deposition is also a major component. Cypress litter fall

as well as duckweed production and decomposition rates were obtained

from previous studies (Deghi 1977 and Price 1975b, respectively.

Differential equations describing the change in organic matter

accumulation in each dome were written for labile and refractory com-

ponents of each litter category:

d = J-kQ, (3)


where Q is the quantity of each litter component on the forest floor

expressed as g organic matter/m2 and J is the input of each litter

component expressed as g organic matter/m2-yr.








The natural dome model therefore comprised two equations: fast

and slow components of cypress litter. The sewage dome model con-

tained two additional equations for the fast and slow components of

the duckweed litter. These models were simulated on an EAI MiniAC

analog computer after scaling and plotted directly from the analog

computer with a Hewlett-Packard X-Y recorder. The amount of organic

matter that had accumulated on the floor of the natural dome

(20.3 kg organic matter/m2) was used to establish the initial con-

ditions for the refractory component of the cypress leaves in both

domes. Initial levels of the cypress labile component and both

components of the duckweed were set at zero.

An analysis of variance by the least squares method was used to

test the closeness of fit of the observed cypress leaf decomposition

rates to two decomposition models: 1) the two-compartment model,

-klt -k2 t
y = pe1 + (1-p)e (4)

where p is the percentage that undergoes fast decomposition, and

2) the standard exponential decay model (Equation 2). The residual

sum of squares was minimized using the multivariate search procedure

of Hooke and Jeeves (1961). The analysis of variance by the least

squares method was also used to estimate the fast and slow decompo-

sition rate coefficients and the percent of total litter amounts under-

going fast and slow decomposition for the two-compartment model. Only

data from the first six sets of litter bags were used, since later

data were confounded by subsequent litter fall.








Sediments and Peat

A portion of each 5 cm section of core was filled into either a

14 cm3 or 19 cm3 vial and dried at 1050C, weighed, ashed at 5500C

overnight and then reweighed to determine the grams of organic

matter per square meter.

Nitrogen concentration was determined by the micro-Kjeldahl

method after the samples were ground by mortar and pestle. A 100 mg

subsample (dry wt) was mixed with 3 ml concentrated H2SO4, 10 g

K2SO4, and 0.3 g CuSO4 in a 30 ml micro-Kjeldahl flask and allowed to

digest. The flasks were brought up to 30 ml with distilled water,

and 4 ml of 40 percent KOH were added to a 5 ml aliquot of the diges-

tate. This was distilled into 10 ml of a 2 percent boric acid solu-

tion and then titrated with 0.01 N HC1. Duplicate samples were with-

in 5 percent after subtracting the blank. Table 2-4 lists the means,

standard deviations, relative errors, and coefficients of variation

for primary standards and a peat sample. The areal concentration

(g N/m2) calculated for each core was then multiplied by the area

circumscribed by the core location. The amount of nitrogen (kg) cal-

culated for each area was then summed to estimate the total nitrogen

in the swamp floor of each dome.

Oxidation-reduction potentials of the waterlogged swa3mp floors

were measured during dry conditions in July 1977 with an Orion No.

9678 combination electrode positioned 6 2 cm below the sediment sur-

face. Calibration of electrode and potentiometer was checked before

each measurement with a Fe+2/Fe+3 standard solution (Light 1972), and

any deviation from the standard potential of +430 my was compensated

for in the potentials measured on the sediments. Adjustments were




















Table 2-4. Analysis
Kjeldahl
the peat


of the precision and accuracy of the micro-
method used in the determination of total N in
and decomposing leaf litter.


Standard or Sample %N X S.D. Rel. Error C.V.


L-Tyrosine 7.98
7.83
7.50
7.04
7.59 0.42 1.8% 5.5%

Sulfanilimide 15.85
16.05
15.29
15.83
15.14
15.63 0.39 3.9% 2.5%

Peat from center 1.77
of sewage dome 2 1.76
1.82
1.95
1.85
1.83 0.08 -- 4.2%








made in the measured potentials to a standard hydrogen electrode

reference electrode (Light 1972) at pH 7 (Patrick and Mahapatra 1968).

Denitrification

Surface peat samples were collected from the centers of the

Austin Cary natural dome and sewage dome 2 on October 28, 1979, by

immersing containers and displacing the surface water in the con-

tainers with the upper 3 cm of peat. Experiments were initiated in

the lab within three hours of sample collection.

Portions of wet peat (10 ml; 1 g dry weight) were placed in

250-ml Erlenmeyer flasks. The flasks were closed with one-hole neo-

prene stoppers whose bottoms were coated with silicon vacuum grease

(Dow Corning) to prevent N20 absorption. A Nalgene quick-disconnect

connector (9/16 to 3/8 in. diameter) with a serum stopper fastened

at one end was inserted into each one-hole stopper. The flasks were

evacuated three times and refilled with helium to 1.0 atm to render

the flasks anaerobic. Blackmer and Bremner (1977) have reported that

denitrification by soil microorganisms is not significantly affected

by substitution of He for N2 in soil atmosphere.

In order to remove the small amounts of endogenous nitrate (0.03

and 0.05 mg NO3 + NO2 nitrogen/L for the natural and sewage domes,

respectively), the flasks were preincubated 19 h at 24C. Depending

on the treatment, NaNO3 (1 mg NO3--N/L final concentration or 100 pg

NO3 -N/g peat (dry wt)) was added either by itself or in combination

with glucose (20 mg/L final concentration or 0.2 percent by weight

with peat (dry wt)) and/or NaHCO3 (300 mg/L alkalinity as CaCO3 final

concentration). All the above spikes were dissolved in 1 ml deionized

water and added by syringe through the stoppers. In flasks where








inhibition of the N20 reductase was desired, enough C2H2 was injected

to yield a final concentration of 0.094 ml C2H2/ml H20. Excess pressure

was then released by piercing the serum stopper with a hypodermic needle

to attain an initial internal pressure of 1.0 atm. The flasks were

swirled and incubated statically in the dark at 220C. Controls without

C2H2 and added NO3- always showed negligible amounts of N20 production.

The amount of (NO3-+N2- )-N remaining in solution (after compensating

for that remaining in controls) after the incubation period was subtrac-

ted from the 1.0 ppm nitrate nitrogen spike when calculating the per-

centage nitrate denitrified.

In order to determine the amount of N20 dissolved in the peat sus-

pensions and to check for leakage and absorption of N20 by the stoppers,

duplicate flasks prepared as above each received 1 ml of a saturated

HgC12 solution to stop microbial activity. Each flask then received 247

nM N20, and 0.1 atm C2H2 (0.094 ml C2H2/ml H20). The amount of N20 in

the gas phase was determined after equilibration, and the amount dis-

solved in the suspension was calculated as the difference between that

added and that found in the gas phase.

At appropriate intervals, 50 1p of gas phase was removed and

diluted to 500 pl with ambient air in a 1 ml gas-tight syringe (B-D

tuberculin plastic syringe). All flasks were swirled vigorously

prior to gas sampling. Nitrous oxide analysis was made by injection

of 500 pl gas samples into a Tracor 222 gas chromatograph equipped

with a 63Ni electron capture detector. Separation of N20 from other

gases was achieved with a 4 m x 0.32 cm column of Porapack Q (100-120

mesh), using an Ar (95 percent)/methane (5 percent) carrier gas at a

flow rate of 20 ml/min. The column was run at 50C following a








conditioning period at 1500C, and the detector temperature was 3700C.

Full-scale deflection at 1 mV on the recorder corresponded to 2.0 nM

N20/ml gas phase, and minimum detectable N20 concentration in the gas

phase of the bottles was 0.01 nM/ml. Nitrous oxide retention time

was just under 4 minutes. Peak height was linearly proportional to

concentration in the range of 0.01 to 1.0 nM/ml.

Calibration for N20 was carried out by preparing flasks of

standard gas to appropriate concentrations. All results presented

here are means of triplicate flasks, except for the control flasks

poisoned with HgCl2 and spiked with N20 and C2H2. Duplicate flasks

were used for this treatment. Accuracy and precision of the gas

chromatograph and injection techniques employed in the acetylene

blockage experiments are presented in Table 2-5.



Table 2-5. Analysis of the precision and accuracy of the Tracor 222
and Tracor 550 gas chromatographs used in the measure-
ment of N20 during acetylene blockage experiments.


Standard or Sample Range X S.D. Rel. C.V.
(naMi/ml) (nM/ml) (nIM/ml) Error


1.0 nM/ml primary 0.875-1.025 0.969 0.055 3.1% 5.7%
standard injected
into the Tracor
222 gas chromato-
graph

Sample from nitrate- 16.4-18.5 17.3 0.92 -- 5.3%
spiked leaching
column injected
into the Tracor
550 gas chromato-
graph








Nitrification

Surface sediments. Surface sediments from sewage dome 2, sewage

dome 1, groundwater control dome, and Austin Cary natural dome were

obtained on July 2 and July 30, 1978, using two methods. The first

method utilized a sterile 50 cc plastic syringe with a small tygon

tube attached to the aperture. The tygon tubing was then brought

into contact with the surface of the swamp floor while the syringe

remained above the surface water level. The syringe plunger was

then slowly raised while the Tygon tubing was moved over the surface

of the sediments. After the barrel of the syringe was nearly filled

with a sediment-water mixture, the Tygon tubing was removed and the

plastic cap inserted into the needle aperture. The syringe was then

placed in ice and returned to the laboratory. The second method of

sample collection involved piston coring of the peat and sediments.

The cores were stored at 4C until they were extruded in the lab 24 h

after taking the cores in the field. Only the top 2 cm of each core

was used in the MPN test for sutotrophic nitrifiers. In all cases,

duplicate cores and duplicate syringes were taken at each site.

The Most Probable Number (MPN) method of Alexander and Clark

(1965) was used to enumerate autotrophic nitrifiers. Samples were

processed within 24 h of field sampling, and the method was slightly

modified by substituting Bray's nitrate-nitrite powder (Bray 1945) for

the Griess-Ilosvay reagent.

Surface waters. Surface water was collected from the Austin

Cary natural dome on May 3, 1979, and immediately filtered through

a Whatman glass fiber filter (grade 934 AH). A portion of the fil-

trate was then eluted through a DEAE cellulose (Cellex D) column









(bed volume = 50 cc) at a flow rate of 100 ml/h to remove the organic

color. The column, which had been stored in a 0.02 percent NaN3

solution to prevent bacterial contamination, was eluted with 3,000 ml

(equivalent to 60 bed volumes) of .05 M NaCI (pH adjusted to 4.6)

prior to color removal. Both the filtered colored and decolored

water were kept at 40C until the initiation of the experiment 72 h

later.

Two-hundred milliliters of either the colored or decolored water

were poured into BOD5 bottles and spiked with NH4 -N to a final con-

centration of 5 mg NH4 -N/L. The following four treatments were

performed on duplicate bottles:

1. Colored water with pH adjusted to 8.5 with 500 mg NaHCO3/L

2. Decolored water with pH adjusted to 8.5 with 500 mg NaHCO3/L

3. Colored water with pH unadjusted but 350 mg NaCl/L added

4. Decolored water with pH unadjusted but 350 mg NaC1/L added

Table 2-6 lists the initial conditions of the experimental and

control bottles.



Table 2-6. Initial conditions of the experimental and control bottles
for the nitrification experiment on the surface water from
Austin Cary natural dome. Each value is the mean of
duplicate bottles.

SColor (NO3-+NO2-)-N NH -N Alkalinity
Treatment pH (CPU) (mg/L) (mg/L) (mg CaCO3/L)


Experimental
Colored-pH adjusted 8.5 935 0.08 5.1 300
Decolored-pH adjusted 8.5 0 0.08 5.1 300

Control
Colored-pll unadjusted 4.5 705 0.06 5.1 0
Decolored-pH unadjusted 6.1 0 0.07 5.2 0








The pH of 8.5 is within the optimum range for autotrophic nitri-

fication (Engel and Alexander 1958). The high initial alkalinity

(300 mg CaCO3/L) was needed to buffer the medium from the generation

of acid that accompanies nitrification:

NH4 + 202 + 21C03 NO13 + 2H2C03 + H20 (5)


According to the stoichiometry of the above reaction, 7.1 mg of

alkalinity (as CaCO3) is lost per mg of NH4 -N oxidized to NO3-. An

initial alkalinity of 300 mg CaCO3/L thus could titrate the acidity

produced by oxidation of 42 mg NH4 -N/L. Since the initial concen-

tration of NH4+ was only 5 mg N/L, adequate alkalinity was available

to insure a constant pH throughout the experiment.

The NaC1 was added to the two unbuffered controls in order to

maintain an ionic strength equal to that of the pH-buffered experi-

mental bottles.

To insure that an adequate seed of nitrifying organisms would be

present, each BOD bottle was inoculated with 0.2 ml of activated

sludge collected immediately beforehand from the effluent end of the

Gainesville-Kanapaha Sewage Treatment Plant aeration tank. The MPN

method of Alexander and Clark (1965) described above indicated an

autotrophic nitrifier population of 4.9 x 105 cells/ml in the inocu-

lum, yielding 4.9 x 102 cells/ml present initially in the experi-

mental and control bottles.

The bottles were stoppered and incubated in the dark on a shaker

at 22.50C. A 1 ml sample was withdrawn from each bottle for analysis

of ammonium and nitrate plus nitrite periodically over a 195 h incuba-

tion period, and the pll of each bottle was also measured at these times.








Nitrogen fixation

Nitrogenase activity associated with various samples from sewage

dome 2 and Austin Cary natural dome was assayed by the acetylene reduc-

tion method (Stewart et al. 1967; Hardy et al. 1973). Samples col-

lected from each dome included standing water, leaf litter, peat,

lichens (Usnea sp. and Parmelia sp.), Spanish moss (Tillandsia

usneoides), bladderwort (Utricularia sp.), Azolla caroliniana, duck-

weed (Spirodela oligorhiza), and the roots of pond cypress (Taxodium

distichum var. nutans), black gum (Nyssa sylvatica var. biflora), and

buttonbush (Cephalanthus occidentalis). Acetylene was generated from

calcium carbide and water immediately before use. All samples were

analyzed for ethylene by injecting 500 pl of gas into a Varian-

Aerograph model 600 D gas chromatograph with hydrogen flame ioniza-

tion detector and a 2.7-m x 0.3-cm column packed with Poropak R.

Nitrogen was the carrier gas (flow rate = 17 ml/min), and the column

temperature was 56-57C. The air and H2 flow rates were 300 ml/min

and 26 ml/min, respectively. Because of problems associated with

the use of various metabolic poisons in terminating the acetylene

reduction reaction (Jones 1974; Schell and Alexander 1970; Thake and

Rawle 1972), injection into the gas chromatograph was performed

immediately after incubation whenever possible. Amounts of ethylene

were calculated from a calibration curve of peak height determined

with dilutions of pure ethylene. A factor of 1.5 based on the theoret-

ical ratio of 1.5 moles of ethylene produced per mole of ammonia fixed

(Stewart et al. 1967) was used to convert ethylene production rates

to equivalent nitrogen fixation rates (expressed in mg N/g (dry

wt)-h).









In all assays, controls without C2H2 were set up; however, these

almost always proved to be negligible. Ethylene contamination of the

acetylene was always known and allowed for in the final calculations.

Leaf litter, peat, and standing water. Monthly surface litter

and standing water samples were obtained by submerging a 22 or 70-ml

serum bottle to the litter surface, where it was turned upright,

allowing bottom water to displace the air inside. Organic matter

composed almost entirely of cypress and black gum leaf litter was put

in the serum bottles while they were still submerged. The serum

bottles were then brought to the surface and immediately capped with

a rubber serum stopper so that the organic matter was at no time ex-

posed to the air. They were transported back to the lab on ice and

kept refrigerated at 40C until injected with acetylene (within 5 h of

field collection). A high percent aqueous phase was maintained ('80

percent) to avoid exposing the acetylene-reducing organisms to more

oxygen than that present in the bottom waters and to increase the

sensitivity of the acetylene-reduction method (Flett et al. 1976).

Air and acetylene were injected (3 ml air followed by 10 ml acetylene)

to achieve a final concentration of dissolved acetylene of 0.15 ml

C2H2/ml H20. Air and acetylene were injected by pushing a free hypo-

dermic needle through the stopper of an upright serun bottle so that

water was displaced by the gas being injected through a 10 ml glass

syringe, thus maintaining a constant pressure and not exposing the

inside of the serum bottle to more air than injected. The serum bot-

tles were then vigorously shaken by hand for 15-30 s to equilibrate

the vapor and aqueous phases and immediately incubated at in situ

water temperatures in the dark for 3 to 25 h. At the end of the









incubation period, the serum bottles were again vigorously shaken for

1 min to equilibrate the vapor and aqueous phases, before 0.5 ml

was withdrawn for measurement by gas chromatography of ethylene pro-

duction. Corrections for ethylene solubility in an equilibrated

closed system were made according to Henry's Law (Flett et al. 1976).

To determine vertical variation in acetylene reduction activity

(ARA) in peat from the natural dome, two PVC cores were obtained with

a piston-corer on March 8 and April 12, 1979. The cores (with over-

lying water) were sealed by rubber stoppers to prevent exposure to

the air, returned to the laboratory, and extruded within 3 h of sam-

pling. Horizontal slices of 2 cm thickness were made by pushing the

sediment up inside the core tubes with a piston, and slicing off the

sediment at the top. Each 2 cm sample (0-2 cm, 3-5 cm, 6-8 cm, and

8-10 cm) was divided into four subsamples, of which three were incu-

bated under C2H2 and one incubated without C2H2 (as a control for

endogenous production of C2H2), using the procedures already described

for surface litter assays. Both control and experimental serum

bottles were purged with He prior to injection with acetylene to

maintain anoxic conditions during the incubation period.

Surface water was assayed regularly to determine the amount of

fixation accounted for by the water used to prepare the peat and

litter samples for acetylene reduction.

Floating and submerged macrophytes. Samples of macrophytes

Azolla caroliniana, Spirodela oligorhiza, Lemna perpusilla, and

Utricularia sp. were incubated in an aerobic atmosphere injected with

acetylene to yield 12-17 percent acetylene in the gas phase. Two to

three replicate samples were incubated under ambient light conditions








simultaneously with 1-2 samples incubated in the dark. Care was

taken to equalize the pressure of injected materials. After acetylene

addition the 70 ml glass serum bottles (57 percent aqueous phase)

fitted with airtight rubber serum caps were incubated for 1 h at

ambient water temperatures under natural sunlight. Duplicate sets of

controls were incubated simultaneously. One set of controls con-

sisted of a macrophyte sample with no acetylene injected; the other

set was injected with 2 ml formalin prior to acetylene injection.

Control ethylene peaks were always low to undetectable. Peak heights

of the controls were subtracted from peak heights of the samples

after corrections for ethylene solubility in an equilibrated closed

system were made according to Henry's Law (Flett et al. 1976). After

incubation, biological activity was terminated with 2 ml of formalin.

To avoid possible leakage, serum caps were wrapped with masking tape;

and to avoid possible contamination from the rubber serum stoppers,

areas exposed to acetylene during incubation were coated with petro-

leum jelly.

For Azolla, one to three 0.25 m2 plots were harvested from each

dome, and the dry weight biomass determined for each assay to obtain

an areal rate (g N fixed/m2-h). Daily N2-fixation was estimated by

multiplying mean hourly values of the light bottles by 14. Nitro-

genase activity was assumed to be negligible at night (Brotonegoro

and Abdulkadir 1976). Yearly values were estimated by integrating

the daily rates associated with the period of activity. The area

covered by Azolla at the time of incubation was estimated by assuming

the area to be rectangular in shape and then multiplying the measured

distance of two of its sides.









Rhizosphere-endorhizosphere of woody vegetation. Nitrogenase

activity was measured on washed excised roots (<0.4 cm in diameter)

from three major tree species (Taxodium distichum var. nutans, Nyssa

sylvatica var. biflora, and Cephalanthus occidentalis) by the acetylene

reduction method (Stewart et al. 1967). Whole plants or excised roots

were taken from the Austin Cary natural dome between August 1978 and

August 1979. In addition, pond cypress roots were taken from sewage

dome 2 on March 10, 1979, and a pond cypress tree was taken from the

margin of a soft lake (Newnans Lake) near Gainesville on October 23,

1978. In the pond cypress root experiments, small trees (DBH = 2-6

cm; height = 182-467 cm) with intact roots were transported in a

bucket containing substrate back to the laboratory where the roots

were excised. Roots of all other trees were excised in the field, and

2-4 h elapsed between sample collection and C2H2 addition (0.1 atm)

to excised roots in assay containers. All excised roots were washed

free of soil with de-ionized water before being inserted (0.7-4.0 g

(fresh wt)) into assay containers (9.5-70 ml) and were incubated

either aerobically (ambient air) or anaerobically (He). Incubations

were carried out in the dark at room temperature (24-260C) with de-

ionized water or dome water added (filling 10 percent of the container

volume) to keep the atmosphere saturated with w.ater. Each C2H2 incu-

bation consisted of 3-8 replicates.

Gas samples for analysis of C2H4 by gas chromatography were with-

drawn on at least four occasions during the ensuing 24-120 h. Acety-

lene reduction activity was calculated from the linear phase of C2H4

production, which generally followed a lag period of 10 to 20 h.








Incubations without C2H2 to determine background C2H4 consistently

yielded negligible quantities of C2H4.

A surface sterilization experiment was conducted on the roots of

a 366-cm tall cypress tree (3 cm DBH). The roots were excised in the

lab. One-third were immersed (except the proximal cut end) in 10

percent chloramine T (Eastman; C7H7C1NO2SNa-3H20), another third were

immersed (except the proximal cut end) in 1 percent chloramine T, and

the remaining third were immersed in 0.05 M sterile phosphate buffer

(pH = 7) for 30 minutes, followed by two washes in sterile distilled

water. All controls and experimental assay bottles (70 ml capacity)

contained 25 ml in situ water in addition to the excised roots. Pres-

sure within the incubation containers was maintained at 1 atm by

either bleeding excess pressure with a syringe after adding 5 ml (0.1

atm) C2H2 or replacing each 0.5 ml of gas phase withdrawn for injec-

tion into the gas chromatograph by 0.5 ml He. In situ water incubated

without excised roots in the presence of C2H2 produced negligible

amounts of C2H4.














CHAPTER THREE
THE EFFECT OF SECONDARY SEWAGE EFFLUENT ON THE SURFACE AND
GROUNDWATER QUALITY OF CYPRESS DOMES

This chapter summarizes the basic water quality data over the

five-year period beginning March 1974 and ending in May 1979. Its

primary intent is to assess the capability of cypress domes to treat

domestic sewage effluent from a water quality standpoint. Emphasis

is placed on the parameters considered to be most important as pol-

luting substances in the application of treated sewage to cypress

domes.

Standing Water quality

Surface water in pristine cypress domes (e.g., the Austin Cary

dome) is typically very soft, acidic, and highly colored (Table 3-1).

The dominant ions (Na and Cl) are derived from rainfall and are present

in the surface waters at levels similar to those of bulk precipitation

(cf. Chapter 4). In contrast, the surface water of sewage domes 1 and

2 changed considerably with the addition of sewage--to less acidic

(pH 6.2-6.4), hard, and turbid. Sodium and chloride concentrations

increased greatly (Table 3-1), reflecting dietary use of salt,

and remained the dominant ions. Calcium and magnesium (total hard-

ness = 62.5 mg CaCO3/L) and alkalinity concentrations (59.4 mg

CaCO3/L) were also much higher in the sewage domes than in the natural

dome, reflecting the origin of the water from the artesian Floridan

Aquifer. Dissolved solids (as indicated by specific conductance) in-

creased more than five-fold, from a mean value of 60 pmho/cm in the









Table 3-1. Summary of the mean concentrations and standard deviations of
selected chemical parameters for standing waters from March 1974
to May 1979. All values as mg/L unless otherwise noted.


Groundwater
Parameter Austin Cary Control Dome Sewage Dome 1 Sewage Dome 1
center center edgea


Alk (mg CaCO3/L)

pHb

Eh7(mV)

Color (CPU)

Turb (FTU)

Cond (pmho/cm)

0.0.

BOD5

Si

Inorganic C

Organic C

HCO3

Chloride

Fluoride

Sulfate

H2 S

Calcium

Magnesium

Sodium

Potassium

(NO- + NO-) N

NH4 N
4


1.8 2.9

4.51+ 0.36



456 +162

2.8 8.7

60 17

2.03 1.79

2.9 + 1.5

2.0 + 1.7

7.1 + 5.7

39.9 12.9

2.2 3.5

8.2 + 4.2

0.03 0.01

2.6 + 2.7

<0.011 0.00

2.87+ 0.99

1.37 0.59

4.94+ 1.60

0.34 0.24

0.08 0.19

0.14 0.19


157 + 69

6.91+ 0.52

+35c

179 +192

2.0 1.9

368 123

4.39 2.90

2.3 + 1.5

8.3 + 4.7

44.2 + 10.3

28.3 + 33.7

191.5 + 84.0

11.8 4.7

0.41+ 0.17

14.1 6.8

<0.01 0.00

45.94+ 17.14

16.75 5.81

9.36 1.48

0.89 0.39

0.09 0.31

0.20 0.59


91 43

6.13+ 0.64

-185c

334 180

20.8 + 33.0

373 119

0.17 0.38

16.7 + 9.4


23.2 +

30.5 +

110.5 +

57.5

0.38+

28.9

2.00

18.25+

11.59

39.05-

7.96

0.38+

4.2 +


6.7

15.2

52.3

21.9

0.20

11.9

2.06

8.23

7.95

14.97

3.52

0.77

4.7


46 29

5.88+ 0.75

-265c

646 367

8.9 6.9

278 129

0.20 0.71

11.9 6.8


16.2

42.3

56.5

46.3 +

0.22+

17.6

1.06F

10.22+

6.80+

34.04+

6.48+

0.14+

1.9 +


10.8

13.9

35.6

20.3

0.11

18.2

1.16

5.33

3.34

15.19

3.44

0.19

2.4









Table 3-1. extended.


Sewage Dome 1 Sewage Dome 2 Sewage Dome 2 Sewage Dome 2
weira center 40 m north 30 m south


51 21

6.20 0.34



464 211

7.0 + 7.9

266 105

0.48 0.65

8.5 3.8


15.7 +

35.3

61.9

46.4 +

0.34

21.6

0.46+

10.25

5.82+

30.78

5.34+

0.21

1.9


6.7

6.6

25.6

13.5

0.19

13.6

1.4

3.73

1.97

11.94

2.95

0.39

2.1


101 63

6.58 0.30

-255b

311 223

9.2 7.8

461 115

0.29+ 0.70

11.8 6.0

7.5 4.1

23.4 6.2

41.8 35.6

122.7 + 77.2

46.9 18.5

0.44 0.15

34.4 + 12.6

1.09+ 1.74

20.98 7.83

9.60+ 3.39

43.25+ 11.13

8.43+ 3.57

0.27+ 0.35

8.5 + 11.1


43 24

5.92 0.61

-110b

766 301

9.2 9.3

323 104

0.11 0.28


6.0

14.6 +

42.3

52.5 +

46.2

0.28

26.2

2.03

10.37+

6.14

36.69+

6.45

0.17

3.8


2.8

5.9

14.6

29.0

20.9

0.10

13.8

2.12

6.47

2.49

11.64

3.58

0.31

5.1


22 29

5.63 0.78

-95b

878 296

7.8 + 9.3

275 +120

0.88 1.56

7.7 + 5.0

4.4 2.3

9.8 5.6

55.8 15.3

26.9 35.8

55.3 26.1

0.21+ 0.13

15.1 + 13.9

0.10 0.27

6.89 5.16

5.09 3.21

35.91 14.86

5.05 3.14

0.14 0.16

3.1 + 5.4








Table 3-1. continued.


Groundwater
Parameter Austin Cary Control Dome Sewage Dome 1 Sewage Dome 1
center center edgea

Organic N 1.4 1.4 1.0 + 1.0 6.9 7.0 6.0 5.2

Total N 1.6 1.3 1.2 1.4 11.9 8.7 8.1 6.4

Ortho-P 0.07 0.11 0.09 0.11 4.6 2.9 3.3 2.5

Organic P 0.11 0.32 0.18 0.43 2.0 3.1 1.7 + 2.3

Total P 0.18 0.38 0.27+ 0.44 6.5 3.7 4.9 3.7

a Covers the period of sewage pumping only (March 1974 to September 1977).

b H+ is normally distributed; therefore pH is normally distributed and the
mean indicates the central tendency toward a particular value.
c 5-8 cm below sediment surface.









Table 3-1. extended continued.


Sewage Dome 1 Sewage Dome 2 Sewage Dome 2 Sewage Dome 2
weira center 40 m north 30 m south


4.0 4.2 8.4 13.6 5.0 5.0 7.3 10.3

6.3 5.0 17.1 17.7 9.0 6.4 10.6 10.5

3.6 2.0 6.7 7.8 4.1 1.9 3.8 1.8

2.1 2.9 1.7 2.3 2.0 3.0 1.5 1.8

5.8 3.7 8.4 8.2 6.1 2.7 5.3 2.6








natural dome to 329 imho/cm in the sewage-enriched domes. Sulfate

and fluoride also were much higher in the sewage domes than in the

natural dome, reflecting the high levels normally associated with

sewage (Table 3-1).

The dominant ions in the groundwater control dome were calcium

and bicarbonate, reflecting the limestone aquifer that supplies the

water to the dome. Magnesium also was high, suggesting a dolomitic

limestone aquifer, and total alkalinity in the groundwater control

dome was the highest (119 mg CaCO3/L) of the four domes. The mono-

valent/divalent cation ratio was only 0.16 (based on equivalent weight),

indicating the dominance of limestone as a source of dissolved solids

in the groundwater. Both sulfate and fluoride levels were relatively

high in the groundwater control dome, corresponding to the levels of

these ions observed in the groundwater influent. However, levels of

dissolved solids were not so high as those in the sewage domes (Table

3-1).

In the natural dome the mean dissolved oxygen level was 2.0 mg/L.

Higher dissolved oxygen levels (3.8 mg/L) were found in the ground-

water dome, but the sewage domes were usually anoxic because of both

the biological oxygen demand originating from the effluent and the

secondary BOD from induced plant growth. The high levels of sulfate

in the effluent, coupled with the anaerobic condition of the surface

water, frequently resulted in production of sulfide. However, total

organic carbon did not increase with the addition of treated sewage;

for example, TOC averaged 39.9 mg/L in the Austin Cary dome and 30.5

mg/L and 41.8 mg/L in the centers of sewage dome 1 and sewage dome 2,

respectively. Nevertheless, the levels of inorganic carbon accompanying









the treated sewage influent caused the total carbon at the centers of

both sewage domes to increase to concentrations higher than the natural

dome.

Apparent color (determined on raw samples without filtration or

centrifugation) was lower at the centers of the sewage domes and

groundwater control dome than at the Austin Cary dome, but water at

the edges was similar to the natural dome. Addition of treated sewage

resulted in higher levels of turbidity.

Ammonium, organic nitrogen, orthophosphate, and total phosphate

concentrations were much higher in the surface waters of the sewage-

enriched domes than in either control dome (groundwater control dome

and Austin Cary). In addition, ammonium comprised a larger fraction

and organic nitrogen a smaller fraction of the nitrogen in the sewage

domes than in the other two. Nitrate plus nitrite rarely exceeded

10 percent of the total nitrogen concentration in any dome. The

C:N:P ratio was also lowered by the addition of sewage, reflecting the

large amount of phosphorus added with the sewage.

Concentrations of nitrogen and phosphorus species, pH, BOD, Ca,

Mg, Na, K, SO4, inorganic carbon, alkalinity, F, and specific conduc-

tivity decreased from the center of the sewage domes to the edges

(Table 3-1). Chloride decreased From center to 2dge in sewage dome 1

but not in sewage dome 2. On the other hand, concentrations of TOC

and color increased near the edges of the sewage domes. Since the

sewage had high levels of all the above parameters (except TOC and

color) compared to natural cypress dome standing water, the decreasing

concentrations toward the edges may be partially explained by simple

dilution.








Dissolved oxygen levels in the sewage domes were essentially zero

at the center and were very low (often zero) at the edges. This re-

flects both the biochemical oxygen demand of the sewage and low rates

of reaeration in the quiet standing water.

The two edge stations in sewage dome 2 differ some in water qual-

ity. Chemical parameters associated with the incoming sewage (i.e.,

fluoride, SO4, H2S, alkalinity, pH, ortho and total P) were consis-

tently higher at the north station than at the south station of sewage

dome 2.

Concentrations of total and ortho P generally increased with

distance from the center in the groundwater control dome. The ground-

water pumped into the center of this dome has lower levels of nutrients

than are found in surface waters of natural domes (Tables 3-1 and 3-2).

Organic carbon, BOD, K, Na, and color also increased at the edges. On

the other hand, Ca, Mg, F, SO4, inorganic carbon, alkalinity, pH, dis-

solved oxygen, and specific conductivity were more concentrated at the

center of groundwater control dome than at the edges. The variations

in these parameters simply reflect the composition of the groundwater,

which is pumped from a limestone aquifer. The higher concentrations of

dissolved oxygen at the center can be attributed to physical aeration

from the pumping action, to a large standing crop of filamentous algae

(Spirogyra sp.) often present at the center, and to the oxygen demand

and consequently normally depressed dissolved oxygen values of the

colored waters near the edge.








Table 3-2. Summary of the mean concentrations and standard deviations for selected parameters of
composite shallow groundwaters from April 1974 to May 1979. All values as mg/L unless
otherwise noted.


Wells
Deep Control Wells Control Wells Surrounding
Parameter Groundwrater Distant From Surrounding Wells Inside Sewage Dome 1 Well 19
Well Groundwater Groundwater Sewage Dome 1 and
Control Dome Control Dome Sewage Dome 2


Alk (mg CaCO3/L)

pH

Color (CPU)

Turb (FTU)

Cond (umho/cm)

Si

Inorganic C

Organic C

HC03

Chloride

Fluoride

Sulfate

H2S
Calcium


228 +

7.212:

20

1.3 =

432



53.4

6.5=

278.2 -

7.0

0.53

19.4 +


5

0.32

25

1.5

98



4.2

6.2

6.4

5.6

0.21

0.9


13 + 15

5.38 0.66

123 126

63.9 114.9

90 67

3.9 + 1.9

6.4 5.3

17.6 16.9

16.6 17.8

9.6 3.5

0.18 0.18

5.4 5.7


5 9

5.05+ 0.76

132 109

39.0 82.8

173 36

5.1 + 0.9

8.0 7.5

23.2 16.9

6.5 10.7

40.3 6.7

0.12- 0.03

5.1 9.1


25

4.8

53

7.0

125



18.9

13.0

30.0

20.7

0.1

2.6


+ 40 8 26

3 0.76 4.74 0.77

39 230 224

S 8.3 19.8 36.0

61 126 60

--- 4.8 0.3

18.3 11.2 10.3

+ 11.2 26.2 19.9

48.6 10.3 31.8

12.7 36.3 20.5

7 0.18 0.14 0.20

4.7 4.5 + 7.1


48 64

5.74+ 0.57

297 206

53.3 67.5

131 37


8.6

21.4 +

58.8 +

22.0 +

0.72

9.2 +


6.9

35.2

78.0

6.9

0.29

11.3


9.54 8.40 9.23 5.90 7.86 7.47


17.16 5.32
17.16+ 5.32


64.81 7.73


6.95+ 8.18







Magnesium 20.75 4.91 1.50+ 1.24 2.50 0.52 4.18 4.28 1.55 1.13 3.42 0.90

Sodium 9.44+ 1.26 5.62 1.84 10.14 1.50 8.37 2.40 10.04 5.71 5.33+ 1.28

Potassium 0.84: 0.29 0.43 0.34 0.44 0.18 0.35 0.28 0.45 0.36 0.64 0.21

(NO3 + NO2) N 0.03 0.02 0.09 0.18 0.11 0.27 0.03 0.03 0.10 0.26 0.10 0.18

NH4 N 0.04 0.03 0.26 0.94 0.15 0.17 0.07-+ 0.06 0.28 0.29 0.09+ 0.11

Organic N 0.39 0.26 0.62 0.47 0.63 0.56 0.71 0.50 0.70 0.89 1.04 2.15

Total N 0.46= 0.27 0.86+ 0.60 0.83 0.42 0.80 0.49 1.04 0.82 1.23 2.00

Ortho-P 0.05 0.05 0.21 0.33 0.11 0.21 0.08 0.12 0.32+ 1.24 1.8 3.0

Organic P 0.10+ 0.14 0.20 0.24 0.11 0.14 0.09 0.12 0.16 0.34 0.5 0.8

Total P 0.16+ 0.17 0.41+ 0.42 0.21 0.27 0.17 0.17 0.49+ 1.30 2.3 2.9
UN









Surface Water Quality Following the Cessation of Sewage Pumping to
Sewage Dome 1

The treated sewage influent pumped to sewage dome 1 was dis-

continued in September 1977. Sampling was continued on an irregular

schedule (depending on the presence of standing water) for the fol-

lowing 20 months in order to determine the extent of recovery in

surface water quality. Wide variations were observed for most water

quality parameters during this period (Table 3-3). These variations

resulted from two major factors: 1) elapsed time since cessation of

sewage influent; and 2) the frequency, extent, and intensity of rain-

fall prior to sampling.

Thus, because of an extended dry period (October-November 1977),

the first sampling of the surface water during recovery (December 1977)

yielded higher levels of specific conductance, minerals, nutrients,

total carbon, BOD and turbidity than occurred in any other subsequent

period. Higher levels of major cations and sulfate were found than

occurred in sewage dome 1 standing water during sewage loading. The

oxidation of reduced sulfur that had been immobilized as organic mat-

ter or ferrous sulfide under the low redox potential present during

sewage pumping apparently accounted for the unusually high (237 mg/L)

sulfate level after the dry period. Other sampling dates on which

high concentrations were found for the water quality parameters (May

1978, and February and May 1979) were also preceded by dry periods

that resulted in the disappearance of standing water from the dome,

thus allowing a build-up of the products of aerobic decomposition and

oxidation.

The sampling dates on which the lowest concentrations were found

for the water quality parameters (February, March, and August 1978)








Table 3-3. Changes in water quality at the center station
after cessation of sewage loading on September
values as mg/L unless otherwise noted.


of sewage dome 1
16, 1977. All


Conduc-
Date tivity pH Ca Mg Na K SO4 HCO3a C1 F
(Gmho/cm)

8/2/77b 520 6.80 18.3c 11.6c 39. 0 8.0c 28.9d 125.6 63.0 0.65

12/16/77e 547 5.10 41.9 23.2 75.4 12.8 237.0 4.9 65.0 0.13

2/1/78 151 5.00 3.5 3.5 18.2 2.0 9.0 7.3 26.0 0.08

3/7/78 73 3.30 2.3 1.5 7.3 3.9 43.0 0.0 8.5 0.06

5/6/78e 269 5.25 8.6 5.8 24.5 6.7 60.0 8.5 22.5 0.11

8/4/78 35 4.21 2.6 1.0 2.6 2.5 <1.0 0.0 2.5 0.04

2/22/79e 119 4.60 4.8 2.3 13.0 1.3 18.0 0.0 14.2 0.08

5/26/79 100 5.43 4.2 2.0 9.0 1.2 10.0 17.0


a Calculated from H -HCO3 equilibrium using alkalinity.
b
Last date of sampling before cessation of treated sewage loading.

c Mean of 17-18 surface water samples taken at dome center from April 1974 -
August 1976 during sewage loading. No measurements were made from
September 1976 September 1977.
Mean of 5 surface water samples taken at dome center from August 1975 -
March 1977 during sewage loading. No measurements were made from April
1977 September 1977.
e Dry period with no standing water preceded sampling date.








Table 3-3. extended.


Tur-
TC Si BOD5 H2S D.O. bidity Color
(NTU) (CPU)


38.5 26.8

98.0 15.2 18.8

72.0 4.3 3.3

100.5 0.5 2.8

3.9 10.0

57.5 1.3 2.6

3.5

82.0 1.0 2.9


6.2

<0.01

<0.01



<0.01

<0.01

<0.01

<0.01


1.05

0.00

4.25

4.10

0.35

0.00

6.10

0.30


18.0

13.0

4.0

0.0

0.0


NH4-N Org.
N


NO3-N
and
NO2-N


4.10

<0.01

0.02

0.04

<0.01

0.04

0.01

0.03


8.30

4.50

1.50

1.85

0.92

0.22

0.08

1.18


8.10

2.72

1.44

0.69

2.40

0.40

0.50

1.20


~~








were preceded by extensive rainfall that diluted the pollutants re-

maining from the period of sewage loading. On one occasion (August

1978), all water quality parameters except potassium and total phos-

phorus were within the ranges measured for the natural dome.

The effects of the sewage could still be discerned 20 months

after sewage inputs had ceased. Specific conductance, major ions,

fluoride, ammonium, and total phosphorus were still higher than the

mean values reported for the natural dome (see Tables 3-1 and 3-3).

Thus, the sediments and vegetation on the swamp floor continued to

release these substances to the standing waters long after the end of

sewage pumping. However, many important water quality parameters,

including pH, nitrate, BOD, total carbon, H2S, dissolved oxygen, tur-

bidity, color, and silica, returned to natural background levels

within 8 months after discontinuation of sewage pumping.

Removal of Major Pollutants

Conventional Treatment Plant/Dome System

The ability of cypress domes to reduce the levels of sewage

pollutants in their surface and groundwaters is illustrated in Figures

3-1 to 3-4. Stations have been combined into four major groups;

Tables 3-1, 3-2, and 3-4 give the mean values and standard deviations

for the parameters for the surface water and composite groundwater

stations. The first three (package plant and oxidation pond; sewage

dome surface water; and wells) follow the route of the sewage through

the treatment plant and cypress dome system, and the fourth major

grouping represents a control: the surface water of the Austin Cary

dome. The first bar in the treatment plant group represents the raw

sewage influent; the second is treated sewage effluent; the third is

















(170)

(288)




80-


70-
SOrganic C BOD5

60-



z
o*
50-




I-


S20-



0-

Pocko1 n Sewog I Wells Jatural Pockage Sc Plan'I8 Dome Dome Plant a c ene Dome
Ox Por' Surfac Surface Ox Fond Surfcce Surface
VIo er Wcer aer Woter











Figure 3-1. Average concentrations ( 1 S.E.) of organic carbon and
biochemical oxygen demand found at various points within
the conventional treatment plant/dome system and in
natural waters representing control sites over the entire
study period (March 1974-May 1979).


















































Sewage Wells Natural
Dome Dome
Surface Surface
Wo:er Water


Package Sewage Wells Natural
Plant 8 Dome Dome
Ox Pond Surface Surface
Woter Wa tr


Figure 3-2. Average concentrations ( 1 S.E.) of total nitrogen and
total phosphorus found at various points within the
conventional treatment plant/dome system and in natural
waters representing control sites over the entire study
period (March 1974-May 1979).


o'ckoge
Plant 8
Ox Pcnd












55-

50-


45-

40-


35-


E 30-
z
o25-
I-

'20-


15-
0

10-


05
5-


0-


Package Sewage
Plant 8 Dome
O Pond Surface
Wafer


Wells Natural Package Sewagc Wells Natural
Doam Plant & Dme Dme
Surface Ox Pond Surfa Surface
Waler Water Water


Figure 3-3. Average concentrations ( 1 S.E.) of calcium, magnesium, sodium, and potassium found at various
points within the conventional treatment plant/dome system and in natural waters representing
control sites over the entire study period (March 1974-May 1979).


Package Sewco e Vells Noturol Package Sewge Wells Naturcl
Ploat & a Dcme Dome Plant 8 Dome ome
Ox Pond Surfac Surface O Pond Surface Surface
!Water j Vo.ler Water YaIcr























-tr


r S04


T
-L





Poc kas Se''.cgc V'etis Natural
Plcnit Dome Dome
Ox Por:d Surfac Surfoce
SI Water


Figure 3-4. Average concentrations ( 1 S.E.) of chloride, sulfate, and fluoride found at various points
within the conventional treatment plant/dome system and in natural waters representing control
sites over the entire study period (March 1974-May 1979).


S40-

z


- 20-
z

S0-


I I I ;
Pocange Sewcge
Picnl B Dome
Ox Pen, Surlcce
V tler


\Vels


T1
Natural
Dome
Surface
Water









Table 3-4. Summary of the mean concentrations and standard deviations
of selected chemical parameters throughout the treatment
plant/oxidation pond treatment system. All values as mg/L
unless otherwise noted.


Treatment
Parameter Raw Sewagea Planta Oxidation
Influent Effluent Ponda


Alk (mg CaCO3/L)

pH

Color (CPU)

Turb (FTU)

Cond. (Pmho/cm)

D.O.

BOD5

Si


Inorganic C

Organic C

HCO3

Chloride

Fluoride

Sulfate

Calcium

Magnesium

Sodium

Potassium

(NO3 + NO2)

NH N

Organic N


179 54

7.42 0.36









288 147b



47.7 17.8

170.4 70.0

218.6 65.5


25.0

11.8

54.3 +

8.9

- N 0.52+

27.0 +

21.8


12.0d

2.1d

7.4f

1.7f

0.53

15.2

12.6


84 32

7.27 0.56

90 60

7.7 18.0

486 109



18.2 i 23.5b


19.5

81.0

102.4

49.7

0.62

46.6

25.8

13.4

43.8

6.5

5.8

4.3 +

7.2


15.1

86.4

39.0

5.5c

0.22

4.2

11.4e

4.9e

9.19

2.09

5.7h

5.0h

7.9h


115 20

7.57 0.52

179 85

15.0 18.1

444 103



11.9 9.2b


22.8

23.8 +

140.5

48.0

0.43

39.6

21.9

12.4

49.2

8.7

1.8

3.7

4.1 +


8.8

13.9

24.0

0.7

0.18

1.9

8.3d

2.8d

7.6

1.0

1.3

3.8

4.3








Table 3-4. continued.


Treatment
Parameter Raw Sewage Planta Oxidation
Influent Effluent Ponda

Total N 49.6 20.7 18.7 13.4h 9.6 6.3

Ortho-P 7.2 3.5 7.3 3.2h 7.2 2.3

Organic P 4.5 + 4.1 2.0 3.1h 1.3 1.7

Total P 11.7 5.0 9.3 4.4h 8.5 2.9

a Alkalinity, pH, inorganic carbon, organic carbon, calcium, magnesium,
nitrate plus nitrite, ammonium, organic nitrogen, orthophosphorus,
and total phosphorus from Zoltek and Whittaker (1975); Zoltek (1976);
and Zoltek and Neff (1977).
bAlachua County Pollution Control (1974-78); primarily grab samples.

c Overman (1974 and 1975).
d
dCarriker unpublished data (1974-76); Zoltek and Whittaker (1975);
Zoltek (1976); Zoltek and Neff (1977).
e Carriker unpublished data (1974-76); Zoltek and Whittaker (1975);
Zoltek (1976); Zoltek and Neff (1977); Overman (1974 and 1975).

fCarriker (1974-76).

9 Carriker (1974-76); Overman (1974 and 1975).
hOverman (1974 and 1975); Zoltek and Whittaker (1975); Zoltek (1976);
Zoltek and Neff (1977).








the oxidation pond. The sewage dome surface waters are divided into

center (mean of center stations of both sewage domes) and edge (mean

of four stations for both sewage domes) sites. The first of the well

histograms represents the pooled averages of wells within sewage dome

1 and surrounding sewage dome 1 and sewage dome 2 (primarily the

regularly sampled wells B-3, B-5, B-7, B-9, 4A, 8A, and 19); the

second bar is the pooled averages of three wells around groundwater

control dome (wells 24, 30, and 31), and the last bar in this group

is the average of wells distantly removed from the sewage domes

(primarily the regularly sampled wells 22, 28, 33, and 38). (See

Figure 2-2 for well locations.) Ranges and the mean levels for water

quality parameters of individual wells have been previously reported

(Brezonik et al. 1975; Dierberg and Brezonik 1976; Dierberg and

Brezonik 1978).

Large decreases in the concentrations of the major cations and

anions, organic matter, and nutrients were observed between the sur-

face waters of both sewage domes and the wells surrounding the sewage

domes. With the exception of chloride, fluoride, and calcium, the

levels found associated with wells within and surrounding the sewage

domes were the same as those from control wells. The package plant

treatment process resulted in a larger percentage decrease in organic

matter and nitrogen than in the other parameters. Only small reduc-

tions were measured in the surface waters of the sewage domes compared

to the influent levels, with calcium, magnesium, and fluoride being

the exception.









Total organic carbon and biochemical oxygen demand (BOD)

Biochemical oxygen demand values more closely reflect the effect

of sewage effluent on the highly colored surface waters of the cypress

domes than does total organic carbon (TOC) (Figure 3-1). The package

treatment plant removed 94 percent of the BOD of the raw sewage, and

the oxidation pond removed an additional 2 percent. The remaining

BOD was then discharged into the cypress domes where small reductions

(35 to 38 percent) were observed between the centers and edges of

both sewage domes. The groundwater from the four wells surrounding

sewage dome 2 indicated removal to levels below those found in the

natural dome surface water.

The two experimental domes (Figure 3-5) had BOD levels comparable

to the two control domes when the influent pipe to the sewage domes

was located far from the treatment plant (October to February 1976).

Prior to that and thereafter, BOD levels were significantly higher in

both experimental domes, probably from a combination of lower rainfall

and higher levels of organic carbon in the incoming sewage. Reloca-

tion of the influent pipe to a point closer to the discharge from the

treatment plant in late March 1976 increased the input of organic

carbon to the domes (Zoltek and Whittaker 1975 and Zoltek 1976). Mean

TOC values were 12.3 mg/L for the 8 months prior to relocation and

30.2 mg/L For the 14 months after relocation.

The BOD levels for both control domes normally were less than

5 mg/L, whereas the BOD levels in the sewage domes usually were above

5 mg/L, (the standard of the Florida Department of Environmental

Regulation (1965) for finished waters of domestic tertiary sewage

treatment). It should be noted that all BOD samples were filtered











DOME INFLUENT FROM TREATMENT PLANT
DOME INFLUENT FROM OXIDATION POND (DETENTION TIME ~10 D0
SDCME INFLUENT FROM CEHINO BAFFLE (ADJACENT TO TREATMENT
PLANT)


CESSATION OF TREATED
SEWAGE INFLUENT TO S-I

{


*-- AUSTIN CARY
A-.--. G-I
+-+ s-
X---X s-2


i \ ^ \i\ Il I
A 'JA ,A *
A I


Q I
+ 1 x \ i \ 1 X










17 1976 177 DRY 197 RY 1979
JA N I 'JAIIlN I I I I I I I N IJAN 44
76 1976 1977 DRY 1978 C RY U 979
CONDITIONS CO EDITIONS
Figure 3-5. Mean BOD5 levels in the surface waters of control and experimental domes. Each point is the
mean of one center and one or two edge stations for each dome, except Austin Cary where only
the center station is plotted. (G-1 is the groundwater control dome, S-1 is sewage dome 1,
and S-2 is sewage dome 2.)








through Whatman No. 4 qualitative filters to remove duckweed and sedi-

ments before incubation. This procedure gave a better measurement of

BOD levels attributable to the incoming sewage, but it probably re-

sulted in an underestimate of the true BOD levels.

Nitrogen

The package treatment plant substantially reduced the raw nitro-

gen influent levels (from 50 to 19 mg/L at the effluent or a 62 percent

removal (Figure 3-2)). The oxidation pond further reduced the average

concentration by another 19 percent. Higher mean concentrations at

the centers of the sewage domes than in the oxidation pond can be

explained in part by the fact that secondary effluent with higher

concentration was pumped to the domes directly from the treatment

plant during 47 of the 60 months of the study. Nitrogen concentra-

tions in the wells surrounding and within the sewage domes maintained

the same levels as the control wells.

Except for a brief three month period (October 1975 to December

1975), total nitrogen (TN) concentrations in the surface waters of the

sewage-treated domes were clearly higher than in the control domes

(Figure 3-6). The mean TN concentrations for sewage dome 1, sewage

dome 2, Austin Cary, and groundwater control dome over the study period

were 8.6, 12.3, 1.6, and 1.5 mg/L, respectively. The low TN levels

during late 1975 and the increase beginning in February of 1976 reflect

changes in the nature of the incoming sewage effluent, as discussed in

the section on BOD.

The center stations of the sewage domes had higher levels of TN

than did the edge stations. For example, TN was 33 percent lower at

one edge station (n=27) and 44 percent lower at another (n=27) than














z LOVE INFLUENT FROM TREATMENTT PLANT

DOME INFLUENT FROM OXIDATION POND (DETENTION TIME 10 DAYS)

O DOME INFLUENT FROM BEHIND BAFFLE (ADJACENT TO TREATMENT PLANT)

S AUSTIN CARY
A .A- G -I
+-- S- I
X ---Y S-2


CESSATION OF TREATED
SEWAGE INFLUENT TO S-1

i


< 40-




30
<




20
is-

18-
16-
14-
12-
0-
6B
6-
4-

0


NAR
19741
BEGAN PUMPING
TO S-I & 5-2
Figure 3-6.


B.;


I'


SIJAN IJAN IJAN I JAN JAN
1975 1976 1977 DRY 1978 .979
BEGAN PUMPING CONDITIONS tf __
TO 5-2 DRY
Mean total nitrogen levels in the surface waters of control and experimental CONDoiONS
domes. Each point is the mean of one center and one or two edge stations for each dome, except
Austin Cary where only the center station is plotted. (G-1 is the groundwater control dome, S-1
is sewage dome 1, and 5-2 is sewage dome 2.)


/









the average TN (12.7 mg/L) at the center of sewage dome 1. Average

TN levels of the northern and southern edge stations in sewage dome 2

were 41 percent and 31 percent lower (n=31), respectively, than the

center station (15.2 mg N/L). The low redox potentials in the sewage

domes explain the preponderance of ammonium among the inorganic forms

(Table 3-1).

Levels of TN were more variable from month to month than were the

levels of total phosphorus. Perhaps this reflects the more complex

biological cycle of nitrogen. The large temporal fluctuations of TN

concentrations in the surface waters of the sewage domes also may

be explained by several physical factors, including alterations in the

placement of the sewage influent pipe within the oxidation pond, vary-

ing treatment plant efficiencies, and variations in precipitation and

evapotranspiration. High levels of nitrate in the inflowing sewage

tend to be associated with lower TN concentrations in the domes,

because nitrate could be denitrified in the anoxic dome waters. Figure

3-7 supports this possibility; high percentages of nitrate plus nitrite

in the inflowing nitrogen were associated with lower TN concentrations

in the dome centers; most of the nitrate probably was dissimilated to

N2 by denitrifying bacteria (see section on Laboratory Leaching

Studies). Since the sewage domes are anoxic, oxidation of ammonium

to nitrate does not occur. Concentrations of nitrate plus nitrite

were lower in the centers of sewage dome 1 and sewage dome 2 than in

the influent (Tables 3-1 and 3-4). This was not a result of simple

dilution, since the percentage nitrate plus nitrite of the TN in the

centers of both experimental domes was always considerably lower than

the percentage nitrate plus nitrite of the TN in the influent (Figure

3-8).


























9 S-IC
+ S 2C


0

o
4-+


I I I I I I I
10 20 30 ';0 50 60 70 80 90 I

%/ ("03 8 NO ) N of Total N in Influent


Figure 3-7. Total nitrogen in the centers of sewage dome 1 (S-1C) and
sewage dome 2 (S-2C) in relation to the percent nitrate
plus nitrite nitrogen of the total nitrogen in the
influent.


50-





















z
S40-
o











20

I-
i-


60-T----


























Z 70
7- S- IC
2z + S-2C
< 60-
I-
Z 50-


'o' 40-
C5 0
z
30-
2 '
"W 20-
S0 +
+ )
10- '0 4

,"- .--r-- ---,
10 20 30 40 50 60 70 80
o%(N03 8 NO2) cf Tolol N in Influent
















Figure 3-8. Percent nitrate plus nitrite nitrogen in the treated
sewage influent vs. percent nitrate plus nitrite nitrogen
in the centers of sewage done 1 (S-1C) and sewage dome
2 (S-2C).









Total nitrogen levels in the surface waters of sewage dome 1 and

sewage dome 2 generally were lower during the first two years of sew-

age inputs (Figure 3-6), corresponding with a period of higher levels

of nitrate and lower TN levels in the sewage effluent (Overman 1974,

1975; Zoltek and Whittaker 1975; Zoltek 1976). Thus, it appears pos-

sible to maintain some control over the levels of total nitrogen in

the surface waters of cypress domes receiving sewage by maintaining

a nitrified effluent.

Phosphorus

The substantial reductions shown for BOD and nitrogen through the

treatment plant did not occur for phosphorus (Figure 3-2). Only 20

percent of the total phosphorus (TP) was removed by the plant, and

another 7 percent by the oxidation pond. As a result, the concentra-

tions of TP in the sewage domes were nearly the same as those for TN,

even though TN levels were five times higher than TP levels in the

raw sewage. With only one exception, concentrations of TP in the

shallow wells show complete removal of phosphorus within the domes

(Table 3-1). The exception (well 19) is attributed to a naturally

high background level.

Well 19 was always anomalous, yielding turbid samples and high

levels of alkalinity and calcium, in addition to high level- of fluor-

ide and phosphate (Table 3-1). Although the values for those param-

eters never reached the levels in the surface water of sewage dome 1

(with the exception of fluoride), they were consistently higher than

any other well samples (Dierberg and Brezonik 1978). Besides the pos-

sibility of subsurface contamination by sewage percolate, it was also

possible that surface overland flow could be responsible for








contamination of the well water. However, the drainage characteristics

of the area suggest that such flooding would be highly unlikely. Fur-

thermore, since the well was pumped out one day prior to sampling,

overland contamination does not seem likely.

A third possibility exists: the high levels of orthophosphate,

fluoride, calcium and alkalinity could be attributable to a naturally

occurring geological deposit. This explanation is supported by

several chemical, microbiological, mineralogical, radiological, and

lithological facts.

1) If sewage were the cause of the high concentrations, other

ions that have high concentrations in sewage also should have high

concentrations in water from well 19. Sodium, potassium, and ammonium

exhibit comparatively high concentrations in surface water of sewage

dome 1 (Table 3-1), but occur only at background levels in water from

well 19 (Table 3-2). Moreover, fluoride is twice as high in the well

19 water as in standing water of sewage dome 1 (Tables 3-1 and 3-2).

2) Data on total phosphate in soil solution obtained from ceramic

cups placed between the edge of sewage dome 1 and well 19 indicated

no elevated phosphate levels in the subsurface water down to 2 m. The

original depth for well 19 was 4.5 m (Cutright 1974).

3) Fecal coliform numbers from well 19 were consistently low

(Price 1975a; Allinson and Fox 1976).

4) Since fluorapatite (Ca5(P04)3F) is composed of the elements

found in excess at well 19, and since this mineral is a common phos-

phate rock in the area, it seems likely that this mineral is the cause

of the high levels in well 19 water. Based on the solubility equilib-

rium for fluorapatite, a theoretical phosphate concentration of








7.04 x 10-5 M was calculated by using the mean concentrations of Ca,

F, and the mean pH measured for well 19. This compares favorably with

the measured mean of 5.81 x 10-5 M.

5) Further support for this explanation was found in gamma ray

logs of stratigraphic sections from wells A and B located on the north-

west edge of sewage dome 1 (Figure 2-2). Zones of concentrated phos-

phate are indicated by areas of intense gamma radiation of the associ-

ated radon, thorium and uranium. Intense gamma radiation was logged

beginning at 3 m in an interbedded sandy clay and clayey sand (Smith

1975).

6) According to Cutright (1974), who drilled well 19, the core

from 1 to 2.5 m from this well consisted of greyish white clayey sand,

with clay content increasing rapidly with depth. From 2.5 to 4 m, the

core consisted of blue-grey sandy-clay, and from 4 to 5 m only blue

clay was found. The sand-size particles were medium to fine-grained

quartz and the clay was predominantly kaolinite. The sand content

decreased with depth until, between 5 to 6 m, the deposit was pure

blue clay. Cutright believed this to be the top of the Hawthorn

Formation, which provides the phosphorus-rich deposits that are mined

commercially in Florida. Although none of the other wells on the west

and north side of sewage dome 1 (wells 13, 20, 21, and 1) behaved like

well 19, a deeper well (well 33, 4.3 m deep) distant from the sewage

and control domes displayed similar (though lower) levels of fluoride,

phosphate and calcium (Dierberg and Brezonik 1978). Cutright's (1974)

well logs indicated that wells 1 and 19 were drilled 4.6 m deep, while

wells 18, 20, and 21 were drilled to 3.7 m depths. The deeper nature

of well 19 and control well 33 would put them closer to the Hawthorn








Formation. Thus, the high concentrations in well 19 would not seem

to be the result of movement of contaminated water from sewage dome 1.

Concentrations of TP in the surface waters of sewage dome 1 and

sewage dome 2 ranged from 2 to 100 times higher than TP concentrations

in the two control domes (Figure 3-9), which had mean TP concentra-

tions of 0.27 mg/L (groundwater control dome) and 0.18 mg/L (Austin

Cary). Sewage dome 2 consistently had higher concentrations than did

sewage dome 1, and concentrations were generally lower at the edges of

both domes than at the center (Figure 3-9 and Table 3-1). However,

in most instances the decrease was less than 50 percent, and (except

on one occasion in sewage dome 1) concentrations were always higher

than the 1 mg/L standard recommended by the Florida Department of

Environmental Regulation for finished waters of tertiary sewage treat-

ment (FDER 1965). This situation also prevailed at the weir station

of sewage dome 1. Over the entire study period, the average TP at the

weir was 31 percent lower than the average at the center of sewage

dome 1 (7.1 mg/L), and at the site 30 m east of the center of sewage

dome 1 the average was 29 percent less than that at the center. Aver-

age concentrations of TP at the edge stations in sewage dome 2 were

25 percent (north station) and 35 percent (south station) lower than

the average at the center (8.2 rg/L).

The large temporal fluctuations in TP levels in sewage dome 1 and

sewage dome 2 (Figure 3-9) at the beginning of the study reflect the

variable nature of the sewage source. Relocation of the influent pipe

within the oxidation pond in March 1976 to a point closer to the

treatment plant did not result in any observable changes of TP con-

centrations in either the incoming sewage (Zoltek 1976) or the standing


























Figure 3-9. Mean total phosphorus levels in the surface waters of control and experimental domes. Each
point is the mean of the one center and one or two edge stations for each dome, except
Austin Cary where only the center station is plotted. (G-1 is the groundwater control dome,
S-1 is sewage dome 1, and S-2 is sewage dome 2.)





























OI-
13-





7-
1-

0 I





I-
4 "
I I
7- Ir' '

6 -"] '


(26) .
(20) + 0 DOME INFLUENT FROM TREATMENT PLANT

i DOME INFLUENT FROM OXIDATION POND (DETENTION TIME ~10 DAYS)

COME INFLUENT FROM BEHIND BAFFLE (ADJACENT TO TREATMENT
PLANT)


CESSATION OF
SEWAGE INFLI


AUSTIN CARY
1 ..........1 G -
S+----+ S-1
S--x S-2












4, +
Si,
,, /\ / \





I A ."


/ */. ..


MAR 1974l JAN 1975
BEGIN PUMPING BEGIN PUMPING TO S-2
TO S-I G-i


IJAN 1976


IJAN 1977 c O
DRY CONDITIONS


I JAN 978


JDRY CON979

DRY CONDITIONS


+ 1


i I


* TREATED
UENT TO S-I


* *- . .


.-.I


I I I I I l I


1 1 1 1 1 1


X


).
......6 ,.....


-c? i -L`:-s3-r-J;-~


i
'"^tr -.i









water of sewage dome 1 and sewage dome 2 (Figure 3-9). As mentioned

previously, this was not the case for levels of BOD and TN. It is

also noteworthy that much of the TP in the sewage domes was ortho-

phosphate (Table 3-1), which is readily utilized as a nutrient by

plants.

Sodium and potassium

The monovalent cations were similar to phosphorus in their pattern

of reduction (Figure 3-3). Reductions of 77 percent for sodium and

95 percent for potassium were found in the wells compared to the

levels in the surface water at the centers of the two sewage domes.

During 1978 and 1979, sodium levels in the wells surrounding sewage

dome 2 increased to concentrations approximately half those found in

the surface water. This increase may be the result of continual trans-

piration from the shallow groundwater aquifer.

Calcium and magnesium

Concentrations of the divalent cations were relatively constant

through the treatment plant and oxidation pond, but they were lower

(52 percent for Ca and 44 percent for hg) at the edges of the sewage

domes than at the centers (Figure 3-3). In comparison, little change

was noted in monovalent cations between the centers and edges. The

decreased concentrations of divalent cations may reflect fixation onto

exchange sites of the sediments. Concentrations of Mg in the ground-

water under and surrounding the two sewage domes were equal to back-

ground levels measured in the control wells, and Ca levels were lower

in the wells near the sewage domes than in the natural control wells.

The proximity of the calcareous Hawthorn Formation to the control wells

probably explains these differences, since these wells were drilled








deeper (ave. depth = 4.27 m) than the wells surrounding the ground-

water control dome and sewage dome 2 (ave. depth = 3.66 m) (Cutright

1974).

Sulfate

A considerable decrease in the concentration of sulfate (39

percent) occurred between the center and edge stations of the sewage

domes, primarily because of the reduction of sulfate to sulfide

(Figure 3-4). Sulfate levels in the wells were similar to those in

the control wells.

Chloride

Because of dietary use of salt, chloride concentrations were

higher in domestic sewage than in most freshwaters. Because chloride

is also a conservative ion (i.e., it is not adsorbed by soil compon-

ents or assimilated by plants), it serves as a crude tracer of sewage.

Levels of chloride in the wells thought to be influenced by sewage

percolation were more than half the values found in the sewage dome

centers (Figure 3-4). Average C1 concentrations were the same from

the raw sewage to the dome edges, pointing to the conservative nature

of chloride. The higher chloride concentrations in the wells sur-

rounding groundwater control dome are unexplainable since the ground-

water pumped into this dome has low chloride levels ('7 mg/L). How-

ever, since the phosphate mineral, apatite, can contain chloride (Hem

1970; Krauskopf 1967), it is possible that the hydroxide ions associ-

ated with the influent from the Floridan Aquifer (median pH = 7.2)

may substitute for chloride ions on the mineral surfaces. During 1978

and 1979, chloride levels in the wells surrounding sewage dome 2 in-

creased to concentrations comparable to those in the surface water




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs